[llvm] VectorCombine: fix logical error after m_Trunc match (PR #91201)
Ramkumar Ramachandra via llvm-commits
llvm-commits at lists.llvm.org
Mon May 6 06:03:42 PDT 2024
https://github.com/artagnon created https://github.com/llvm/llvm-project/pull/91201
The matcher m_Trunc() matches an Operator with a given Opcode, which could either be an Instruction or ConstExpr. VectorCombine::foldTruncFromReductions() incorrectly assumes that the pattern matched is always an Instruction, and attempts a cast. Fix this.
Fixes #88796.
-- 8< --
Based on #91200.
>From ccbdff0590a0730d7143b930d5ab915107113dfa Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <r at artagnon.com>
Date: Mon, 6 May 2024 13:43:01 +0100
Subject: [PATCH 1/2] VectorCombine: add test for crash #88796
---
llvm/test/Transforms/VectorCombine/pr88796.ll | 11 +++++++++++
1 file changed, 11 insertions(+)
create mode 100644 llvm/test/Transforms/VectorCombine/pr88796.ll
diff --git a/llvm/test/Transforms/VectorCombine/pr88796.ll b/llvm/test/Transforms/VectorCombine/pr88796.ll
new file mode 100644
index 00000000000000..d5cd52e11d39d7
--- /dev/null
+++ b/llvm/test/Transforms/VectorCombine/pr88796.ll
@@ -0,0 +1,11 @@
+; REQUIRES: asserts
+; RUN: not --crash opt -passes=vector-combine -disable-output %s
+
+define i32 @test() {
+entry:
+ %0 = tail call i16 @llvm.vector.reduce.and.nxv8i16(<vscale x 8 x i16> trunc (<vscale x 8 x i32> shufflevector (<vscale x 8 x i32> insertelement (<vscale x 8 x i32> poison, i32 268435456, i64 0), <vscale x 8 x i32> poison, <vscale x 8 x i32> zeroinitializer) to <vscale x 8 x i16>))
+ ret i32 0
+}
+
+declare i16 @llvm.vector.reduce.and.nxv8i16(<vscale x 8 x i16>)
+
>From c950394a37f66e10d1009c1ce3e3cba536c03894 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <r at artagnon.com>
Date: Mon, 6 May 2024 13:46:09 +0100
Subject: [PATCH 2/2] VectorCombine: fix logical error after m_Trunc match
The matcher m_Trunc() matches an Operator with a given Opcode, which
could either be an Instruction or ConstExpr.
VectorCombine::foldTruncFromReductions() incorrectly assumes that the
pattern matched is always an Instruction, and attempts a cast. Fix this.
Fixes #88796.
---
llvm/lib/Transforms/Vectorize/VectorCombine.cpp | 3 +--
llvm/test/Transforms/VectorCombine/pr88796.ll | 9 +++++++--
2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
index bbb70134870ab6..50a8209b465168 100644
--- a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
+++ b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
@@ -1961,7 +1961,6 @@ bool VectorCombine::foldTruncFromReductions(Instruction &I) {
if (!match(ReductionSrc, m_OneUse(m_Trunc(m_Value(TruncSrc)))))
return false;
- auto *Trunc = cast<CastInst>(ReductionSrc);
auto *TruncSrcTy = cast<VectorType>(TruncSrc->getType());
auto *ReductionSrcTy = cast<VectorType>(ReductionSrc->getType());
Type *ResultTy = I.getType();
@@ -1969,7 +1968,7 @@ bool VectorCombine::foldTruncFromReductions(Instruction &I) {
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
InstructionCost OldCost =
TTI.getCastInstrCost(Instruction::Trunc, ReductionSrcTy, TruncSrcTy,
- TTI::CastContextHint::None, CostKind, Trunc) +
+ TTI::CastContextHint::None, CostKind) +
TTI.getArithmeticReductionCost(ReductionOpc, ReductionSrcTy, std::nullopt,
CostKind);
InstructionCost NewCost =
diff --git a/llvm/test/Transforms/VectorCombine/pr88796.ll b/llvm/test/Transforms/VectorCombine/pr88796.ll
index d5cd52e11d39d7..4f26f5dcbb928d 100644
--- a/llvm/test/Transforms/VectorCombine/pr88796.ll
+++ b/llvm/test/Transforms/VectorCombine/pr88796.ll
@@ -1,7 +1,12 @@
-; REQUIRES: asserts
-; RUN: not --crash opt -passes=vector-combine -disable-output %s
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -passes=vector-combine -S %s | FileCheck %s
define i32 @test() {
+; CHECK-LABEL: define i32 @test() {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = tail call i16 @llvm.vector.reduce.and.nxv8i16(<vscale x 8 x i16> trunc (<vscale x 8 x i32> shufflevector (<vscale x 8 x i32> insertelement (<vscale x 8 x i32> poison, i32 268435456, i64 0), <vscale x 8 x i32> poison, <vscale x 8 x i32> zeroinitializer) to <vscale x 8 x i16>))
+; CHECK-NEXT: ret i32 0
+;
entry:
%0 = tail call i16 @llvm.vector.reduce.and.nxv8i16(<vscale x 8 x i16> trunc (<vscale x 8 x i32> shufflevector (<vscale x 8 x i32> insertelement (<vscale x 8 x i32> poison, i32 268435456, i64 0), <vscale x 8 x i32> poison, <vscale x 8 x i32> zeroinitializer) to <vscale x 8 x i16>))
ret i32 0
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