[AMDGPU] Fixed crash in getLastMIForRegion when the region is empty. #168653
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PreRARematStage builds region live-outs if GCN trackers are enabled. If rematerialization leads to empty regions, this can cause a crash because of dereference of an invalid iterator in getLastMIForRegion. The fix is to skip calling getLastMIForRegion for empty regions. This patch fixes another bug in the same code region. getLastMIForRegion calls skipDebugInstructionsBackward which may immediately return the RegionEnd if it is not the begin instruction and it is a non-debug instruction. That would imply considering an instruction that is outside the relevant region. The fix is to always pass the previous of RegionEnd to skipDebugInstructionsBackward. This bug was found while using GCN trackers on the existing LIT test machine-scheduler-sink-trivial-remats.mir. Here's the assertion failure. llvm-project/llvm/include/llvm/ADT/ilist_iterator.h:168: llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::reference llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::operator*() const [with OptionsT = llvm::ilist_detail::node_options<llvm::MachineInstr, true, true, void, false, void>; bool IsReverse = false; bool IsConst = false; llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::reference = llvm::MachineInstr&]: Assertion `!NodePtr->isKnownSentinel()' failed.
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@llvm/pr-subscribers-backend-amdgpu Author: Dhruva Chakrabarti (dhruvachak) ChangesPreRARematStage builds region live-outs if GCN trackers are enabled. If rematerialization leads to empty regions, this can cause a crash because of dereference of an invalid iterator in getLastMIForRegion. The fix is to skip calling getLastMIForRegion for empty regions. This patch fixes another bug in the same code region. getLastMIForRegion calls skipDebugInstructionsBackward which may immediately return the RegionEnd if it is not the begin instruction and it is a non-debug instruction. That would imply considering an instruction that is outside the relevant region. The fix is to always pass the previous of RegionEnd to skipDebugInstructionsBackward. This bug was found while using GCN trackers on the existing LIT test machine-scheduler-sink-trivial-remats.mir. Here's the assertion failure. llvm-project/llvm/include/llvm/ADT/ilist_iterator.h:168: llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::reference llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::operator*() const [with OptionsT = llvm::ilist_detail::node_options<llvm::MachineInstr, true, true, void, false, void>; bool IsReverse = false; bool IsConst = false; llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::reference = llvm::MachineInstr&]: Assertion `!NodePtr->isKnownSentinel()' failed. Patch is 703.84 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/168653.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp b/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
index ba458ea4b519d..c8ce3aab3f303 100644
--- a/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
@@ -978,10 +978,8 @@ GCNScheduleDAGMILive::getRealRegPressure(unsigned RegionIdx) const {
static MachineInstr *getLastMIForRegion(MachineBasicBlock::iterator RegionBegin,
MachineBasicBlock::iterator RegionEnd) {
- auto REnd = RegionEnd == RegionBegin->getParent()->end()
- ? std::prev(RegionEnd)
- : RegionEnd;
- return &*skipDebugInstructionsBackward(REnd, RegionBegin);
+ assert(RegionBegin != RegionEnd && "Region must not be empty");
+ return &*skipDebugInstructionsBackward(std::prev(RegionEnd), RegionBegin);
}
void GCNScheduleDAGMILive::computeBlockPressure(unsigned RegionIdx,
@@ -1076,9 +1074,12 @@ GCNScheduleDAGMILive::getRegionLiveOutMap() const {
assert(!Regions.empty());
std::vector<MachineInstr *> RegionLastMIs;
RegionLastMIs.reserve(Regions.size());
- for (auto &[RegionBegin, RegionEnd] : reverse(Regions))
+ for (auto &[RegionBegin, RegionEnd] : reverse(Regions)) {
+ // Skip empty regions.
+ if (RegionBegin == RegionEnd)
+ continue;
RegionLastMIs.push_back(getLastMIForRegion(RegionBegin, RegionEnd));
-
+ }
return getLiveRegMap(RegionLastMIs, /*After=*/true, *LIS);
}
@@ -1088,10 +1089,12 @@ void RegionPressureMap::buildLiveRegMap() {
RegionLiveRegMap =
IsLiveOut ? DAG->getRegionLiveOutMap() : DAG->getRegionLiveInMap();
for (unsigned I = 0; I < DAG->Regions.size(); I++) {
+ auto &[RegionBegin, RegionEnd] = DAG->Regions[I];
+ // Skip empty regions.
+ if (RegionBegin == RegionEnd)
+ continue;
MachineInstr *RegionKey =
- IsLiveOut
- ? getLastMIForRegion(DAG->Regions[I].first, DAG->Regions[I].second)
- : &*DAG->Regions[I].first;
+ IsLiveOut ? getLastMIForRegion(RegionBegin, RegionEnd) : &*RegionBegin;
IdxToInstruction[I] = RegionKey;
}
}
diff --git a/llvm/test/CodeGen/AMDGPU/machine-scheduler-gcn-trackers-sink-trivial-remats.mir b/llvm/test/CodeGen/AMDGPU/machine-scheduler-gcn-trackers-sink-trivial-remats.mir
new file mode 100644
index 0000000000000..5491008d4cb8a
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/machine-scheduler-gcn-trackers-sink-trivial-remats.mir
@@ -0,0 +1,8844 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn -mcpu=gfx908 -run-pass=machine-scheduler -amdgpu-disable-unclustered-high-rp-reschedule -amdgpu-use-amdgpu-trackers -verify-machineinstrs %s -o - | FileCheck -check-prefix=GFX908 %s
+# RUN: llc -mtriple=amdgcn -mcpu=gfx908 -passes=machine-scheduler -amdgpu-disable-unclustered-high-rp-reschedule -amdgpu-use-amdgpu-trackers %s -o - | FileCheck -check-prefix=GFX908 %s
+
+---
+name: test_occ_10_max_occ_no_sink
+tracksRegLiveness: true
+machineFunctionInfo:
+ isEntryFunction: true
+body: |
+ ; GFX908-LABEL: name: test_occ_10_max_occ_no_sink
+ ; GFX908: bb.0:
+ ; GFX908-NEXT: successors: %bb.1(0x80000000)
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 0, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_1:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 1, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_2:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 2, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_3:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 3, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_4:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 4, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_5:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 5, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_6:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 6, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_7:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 7, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_8:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 8, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_9:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 9, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_10:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 10, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_11:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 11, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_12:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 12, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_13:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 13, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_14:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 14, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_15:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 15, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_16:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 16, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_17:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 17, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_18:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 18, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_19:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 19, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_20:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 20, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_21:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 21, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_22:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 22, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_23:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 23, implicit $exec, implicit $mode
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: bb.1:
+ ; GFX908-NEXT: successors: %bb.2(0x80000000)
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: S_NOP 0
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: bb.2:
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_]], implicit [[V_CVT_I32_F64_e32_1]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_2]], implicit [[V_CVT_I32_F64_e32_3]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_4]], implicit [[V_CVT_I32_F64_e32_5]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_6]], implicit [[V_CVT_I32_F64_e32_7]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_8]], implicit [[V_CVT_I32_F64_e32_9]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_10]], implicit [[V_CVT_I32_F64_e32_11]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_12]], implicit [[V_CVT_I32_F64_e32_13]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_14]], implicit [[V_CVT_I32_F64_e32_15]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_16]], implicit [[V_CVT_I32_F64_e32_17]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_18]], implicit [[V_CVT_I32_F64_e32_19]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_20]], implicit [[V_CVT_I32_F64_e32_21]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_22]], implicit [[V_CVT_I32_F64_e32_23]]
+ ; GFX908-NEXT: S_ENDPGM 0
+ bb.0:
+ successors: %bb.1
+
+ %0:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 0, implicit $exec, implicit $mode, implicit-def $m0
+ %1:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 1, implicit $exec, implicit $mode, implicit-def $m0
+ %2:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 2, implicit $exec, implicit $mode, implicit-def $m0
+ %3:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 3, implicit $exec, implicit $mode, implicit-def $m0
+ %4:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 4, implicit $exec, implicit $mode, implicit-def $m0
+ %5:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 5, implicit $exec, implicit $mode, implicit-def $m0
+ %6:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 6, implicit $exec, implicit $mode, implicit-def $m0
+ %7:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 7, implicit $exec, implicit $mode, implicit-def $m0
+ %8:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 8, implicit $exec, implicit $mode, implicit-def $m0
+ %9:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 9, implicit $exec, implicit $mode, implicit-def $m0
+ %10:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 10, implicit $exec, implicit $mode, implicit-def $m0
+ %11:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 11, implicit $exec, implicit $mode, implicit-def $m0
+ %12:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 12, implicit $exec, implicit $mode, implicit-def $m0
+ %13:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 13, implicit $exec, implicit $mode, implicit-def $m0
+ %14:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 14, implicit $exec, implicit $mode, implicit-def $m0
+ %15:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 15, implicit $exec, implicit $mode, implicit-def $m0
+ %16:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 16, implicit $exec, implicit $mode, implicit-def $m0
+ %17:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 17, implicit $exec, implicit $mode, implicit-def $m0
+ %18:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 18, implicit $exec, implicit $mode, implicit-def $m0
+ %19:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 19, implicit $exec, implicit $mode, implicit-def $m0
+ %20:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 20, implicit $exec, implicit $mode, implicit-def $m0
+ %21:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 21, implicit $exec, implicit $mode, implicit-def $m0
+ %22:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 22, implicit $exec, implicit $mode, implicit-def $m0
+ %23:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 23, implicit $exec, implicit $mode
+
+ bb.1:
+ successors: %bb.2
+
+ S_NOP 0
+
+ bb.2:
+
+ S_NOP 0, implicit %0, implicit %1
+ S_NOP 0, implicit %2, implicit %3
+ S_NOP 0, implicit %4, implicit %5
+ S_NOP 0, implicit %6, implicit %7
+ S_NOP 0, implicit %8, implicit %9
+ S_NOP 0, implicit %10, implicit %11
+ S_NOP 0, implicit %12, implicit %13
+ S_NOP 0, implicit %14, implicit %15
+ S_NOP 0, implicit %16, implicit %17
+ S_NOP 0, implicit %18, implicit %19
+ S_NOP 0, implicit %20, implicit %21
+ S_NOP 0, implicit %22, implicit %23
+ S_ENDPGM 0
+...
+---
+name: test_occ_9_one_block_high_rp_livethrough
+tracksRegLiveness: true
+machineFunctionInfo:
+ isEntryFunction: true
+body: |
+ ; GFX908-LABEL: name: test_occ_9_one_block_high_rp_livethrough
+ ; GFX908: bb.0:
+ ; GFX908-NEXT: successors: %bb.1(0x80000000)
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 0, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_1:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 1, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_2:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 2, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_3:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 3, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_4:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 4, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_5:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 5, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_6:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 6, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_7:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 7, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_8:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 8, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_9:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 9, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_10:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 10, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_11:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 11, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_12:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 12, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_13:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 13, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_14:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 14, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_15:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 15, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_16:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 16, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_17:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 17, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_18:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 18, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_19:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 19, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_20:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 20, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_21:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 21, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_22:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 22, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: bb.1:
+ ; GFX908-NEXT: successors: %bb.2(0x80000000)
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_23:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 24, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_23]]
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: bb.2:
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_24:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 23, implicit $exec, implicit $mode
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_24]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_]], implicit [[V_CVT_I32_F64_e32_1]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_2]], implicit [[V_CVT_I32_F64_e32_3]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_4]], implicit [[V_CVT_I32_F64_e32_5]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_6]], implicit [[V_CVT_I32_F64_e32_7]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_8]], implicit [[V_CVT_I32_F64_e32_9]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_10]], implicit [[V_CVT_I32_F64_e32_11]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_12]], implicit [[V_CVT_I32_F64_e32_13]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_14]], implicit [[V_CVT_I32_F64_e32_15]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_16]], implicit [[V_CVT_I32_F64_e32_17]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_18]], implicit [[V_CVT_I32_F64_e32_19]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_20]], implicit [[V_CVT_I32_F64_e32_21]]
+ ; GFX908-NEXT: S_NOP 0, implicit [[V_CVT_I32_F64_e32_22]]
+ ; GFX908-NEXT: S_ENDPGM 0
+ bb.0:
+ successors: %bb.1
+
+ %0:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 0, implicit $exec, implicit $mode, implicit-def $m0
+ %1:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 1, implicit $exec, implicit $mode, implicit-def $m0
+ %2:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 2, implicit $exec, implicit $mode, implicit-def $m0
+ %3:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 3, implicit $exec, implicit $mode, implicit-def $m0
+ %4:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 4, implicit $exec, implicit $mode, implicit-def $m0
+ %5:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 5, implicit $exec, implicit $mode, implicit-def $m0
+ %6:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 6, implicit $exec, implicit $mode, implicit-def $m0
+ %7:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 7, implicit $exec, implicit $mode, implicit-def $m0
+ %8:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 8, implicit $exec, implicit $mode, implicit-def $m0
+ %9:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 9, implicit $exec, implicit $mode, implicit-def $m0
+ %10:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 10, implicit $exec, implicit $mode, implicit-def $m0
+ %11:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 11, implicit $exec, implicit $mode, implicit-def $m0
+ %12:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 12, implicit $exec, implicit $mode, implicit-def $m0
+ %13:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 13, implicit $exec, implicit $mode, implicit-def $m0
+ %14:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 14, implicit $exec, implicit $mode, implicit-def $m0
+ %15:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 15, implicit $exec, implicit $mode, implicit-def $m0
+ %16:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 16, implicit $exec, implicit $mode, implicit-def $m0
+ %17:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 17, implicit $exec, implicit $mode, implicit-def $m0
+ %18:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 18, implicit $exec, implicit $mode, implicit-def $m0
+ %19:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 19, implicit $exec, implicit $mode, implicit-def $m0
+ %20:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 20, implicit $exec, implicit $mode, implicit-def $m0
+ %21:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 21, implicit $exec, implicit $mode, implicit-def $m0
+ %22:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 22, implicit $exec, implicit $mode, implicit-def $m0
+ %23:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 23, implicit $exec, implicit $mode
+
+ bb.1:
+ successors: %bb.2
+
+ %24:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 24, implicit $exec, implicit $mode, implicit-def $m0
+ S_NOP 0, implicit %24
+
+ bb.2:
+
+ S_NOP 0, implicit %23
+ S_NOP 0, implicit %0, implicit %1
+ S_NOP 0, implicit %2, implicit %3
+ S_NOP 0, implicit %4, implicit %5
+ S_NOP 0, implicit %6, implicit %7
+ S_NOP 0, implicit %8, implicit %9
+ S_NOP 0, implicit %10, implicit %11
+ S_NOP 0, implicit %12, implicit %13
+ S_NOP 0, implicit %14, implicit %15
+ S_NOP 0, implicit %16, implicit %17
+ S_NOP 0, implicit %18, implicit %19
+ S_NOP 0, implicit %20, implicit %21
+ S_NOP 0, implicit %22
+ S_ENDPGM 0
+...
+---
+name: test_occ_9_one_block_high_rp_use_in_high_rp_block
+tracksRegLiveness: true
+machineFunctionInfo:
+ isEntryFunction: true
+body: |
+ ; GFX908-LABEL: name: test_occ_9_one_block_high_rp_use_in_high_rp_block
+ ; GFX908: bb.0:
+ ; GFX908-NEXT: successors: %bb.1(0x80000000)
+ ; GFX908-NEXT: {{ $}}
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 0, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_1:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 1, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_2:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 2, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e32_3:%[0-9]+]]:vgpr_32 = nofpexcept V_CVT_I32_F64_e32 3, implicit $exec, implicit $mode, implicit-def $m0
+ ; GFX908-NEXT: [[V_CVT_I32_F64_e3...
[truncated]
|
🐧 Linux x64 Test Results
|
lucas-rami
reviewed
Nov 19, 2025
llvm/test/CodeGen/AMDGPU/machine-scheduler-gcn-trackers-sink-trivial-remats.mir
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For reference, here is the relevant part of the stack trace. |
lucas-rami
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Nov 19, 2025
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LGTM, thanks for the fix
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PreRARematStage builds region live-outs if GCN trackers are enabled. If rematerialization leads to empty regions, this can cause a crash because of dereference of an invalid iterator in getLastMIForRegion. The fix is to skip calling getLastMIForRegion for empty regions.
This patch fixes another bug in the same code region. getLastMIForRegion calls skipDebugInstructionsBackward which may immediately return the RegionEnd if it is not the begin instruction and it is a non-debug instruction. That would imply considering an instruction that is outside the relevant region. The fix is to always pass the previous of RegionEnd to skipDebugInstructionsBackward.
This bug was found while using GCN trackers on the existing LIT test machine-scheduler-sink-trivial-remats.mir. Here's the assertion failure.
llvm-project/llvm/include/llvm/ADT/ilist_iterator.h:168: llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::reference llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::operator*() const [with OptionsT = llvm::ilist_detail::node_options<llvm::MachineInstr, true, true, void, false, void>; bool IsReverse = false; bool IsConst = false; llvm::ilist_iterator<OptionsT, IsReverse, IsConst>::reference = llvm::MachineInstr&]: Assertion `!NodePtr->isKnownSentinel()' failed.