[AMDGPU] SIInstrInfo: Fix resultDependsOnExec for VOPC instructions #134629
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
SIInstrInfo::resultDependsOnExec assumes that operand 0 of a comparison is always the destination of the instruction. This is not true for instructions in VOPC form where it is "src0". Additional unrelated change: Fix spelling mistakes in doc comment.
|
@llvm/pr-subscribers-backend-amdgpu Author: Frederik Harwath (frederik-h) ChangesSIInstrInfo::resultDependsOnExec assumes that operand 0 of a comparison is always the destination of the instruction. This is not true for instructions in VOPC form where it is "src0". This led to a crash in machine-cse. Additional unrelated change: Fix spelling mistakes in doc comment. Full diff: https://github.com/llvm/llvm-project/pull/134629.diff 3 Files Affected:
diff --git a/llvm/lib/CodeGen/MachineCSE.cpp b/llvm/lib/CodeGen/MachineCSE.cpp
index 6d14509c5934f..1ebf7b96a3b94 100644
--- a/llvm/lib/CodeGen/MachineCSE.cpp
+++ b/llvm/lib/CodeGen/MachineCSE.cpp
@@ -278,10 +278,10 @@ static bool isCallerPreservedOrConstPhysReg(MCRegister Reg,
(MRI.reservedRegsFrozen() && MRI.isConstantPhysReg(Reg));
}
-/// hasLivePhysRegDefUses - Return true if the specified instruction read/write
-/// physical registers (except for dead defs of physical registers). It also
-/// returns the physical register def by reference if it's the only one and the
-/// instruction does not uses a physical register.
+/// hasLivePhysRegDefUses - Return true if the specified instruction
+/// reads/writes physical registers (except for dead defs of physical
+/// registers). It also returns the physical register def by reference if it's
+/// the only one and the instruction does not use a physical register.
bool MachineCSEImpl::hasLivePhysRegDefUses(const MachineInstr *MI,
const MachineBasicBlock *MBB,
SmallSet<MCRegister, 8> &PhysRefs,
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
index 61fda0eef6314..4990c9a74f6ee 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -151,6 +151,9 @@ static bool resultDependsOnExec(const MachineInstr &MI) {
// Ignore comparisons which are only used masked with exec.
// This allows some hoisting/sinking of VALU comparisons.
if (MI.isCompare()) {
+ if (SIInstrInfo::isVOPC(MI))
+ return false;
+
const MachineRegisterInfo &MRI = MI.getParent()->getParent()->getRegInfo();
Register DstReg = MI.getOperand(0).getReg();
if (!DstReg.isVirtual())
diff --git a/llvm/test/CodeGen/AMDGPU/si-instr-info-vopc-no-exec.mir b/llvm/test/CodeGen/AMDGPU/si-instr-info-vopc-no-exec.mir
new file mode 100644
index 0000000000000..f1e9447dbd349
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/si-instr-info-vopc-no-exec.mir
@@ -0,0 +1,23 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=amdgcn -mcpu=gfx1010 -run-pass=machine-cse %s -o - | FileCheck %s
+
+---
+name: vopc_comparisons_do_not_depend_on_exec
+tracksRegLiveness: true
+body: |
+ bb.0:
+ ; CHECK-LABEL: name: vopc_comparisons_do_not_depend_on_exec
+ ; CHECK: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
+ ; CHECK-NEXT: V_CMP_EQ_U32_e32 1, killed undef [[DEF]], implicit-def $vcc_lo, implicit $exec
+ ; CHECK-NEXT: [[V_CNDMASK_B32_e32_:%[0-9]+]]:vgpr_32 = V_CNDMASK_B32_e32 16256, undef [[DEF]], implicit $vcc_lo, implicit $exec
+ ; CHECK-NEXT: [[V_LSHLREV_B32_e64_:%[0-9]+]]:vgpr_32 = V_LSHLREV_B32_e64 16, undef [[V_CNDMASK_B32_e32_]], implicit $exec
+ ; CHECK-NEXT: SI_RETURN
+ %0:vgpr_32 = IMPLICIT_DEF
+ V_CMP_EQ_U32_e32 1, killed undef %0, implicit-def $vcc, implicit $exec
+ %1:vgpr_32 = V_CNDMASK_B32_e32 16256, undef %0, implicit $vcc, implicit $exec
+ V_CMP_EQ_U32_e32 1, killed undef %0, implicit-def $vcc, implicit $exec
+ %2:vgpr_32 = V_CNDMASK_B32_e32 16256, undef %0, implicit $vcc, implicit $exec
+ %3:vgpr_32 = V_LSHLREV_B32_e64 16, killed undef %2, implicit $exec
+ %4:vgpr_32 = V_LSHLREV_B32_e64 16, killed undef %1, implicit $exec
+ SI_RETURN
+...
|
arsenm
reviewed
Apr 7, 2025
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
perlfu
reviewed
Apr 8, 2025
arsenm
reviewed
Apr 8, 2025
Co-authored-by: Matt Arsenault <[email protected]>
arsenm
approved these changes
Apr 17, 2025
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/94/builds/6438 Here is the relevant piece of the build log for the reference |
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
…lvm#134629) SIInstrInfo::resultDependsOnExec assumes that operand 0 of a comparison is always the destination of the instruction. This is not true for instructions in VOPC form where it is "src0". This led to a crash in machine-cse. --------- Co-authored-by: Matt Arsenault <[email protected]>
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
…lvm#134629) SIInstrInfo::resultDependsOnExec assumes that operand 0 of a comparison is always the destination of the instruction. This is not true for instructions in VOPC form where it is "src0". This led to a crash in machine-cse. --------- Co-authored-by: Matt Arsenault <[email protected]>
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
…lvm#134629) SIInstrInfo::resultDependsOnExec assumes that operand 0 of a comparison is always the destination of the instruction. This is not true for instructions in VOPC form where it is "src0". This led to a crash in machine-cse. --------- Co-authored-by: Matt Arsenault <[email protected]>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
SIInstrInfo::resultDependsOnExec assumes that operand 0 of a comparison is always the destination of the instruction. This is not true for instructions in VOPC form where it is "src0". This led to a crash in machine-cse.