[llvm] [ValueTracking] Add missing check for two-value PN recurrance matching (PR #152700)
Ivan R. Ivanov via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 8 06:53:25 PDT 2025
https://github.com/ivanradanov updated https://github.com/llvm/llvm-project/pull/152700
>From 7549fd2f17ccb68b8cad59b7b0085afe93ba1ebe Mon Sep 17 00:00:00 2001
From: Ivan Radanov Ivanov <iivanov at nvidia.com>
Date: Fri, 8 Aug 2025 05:07:40 -0700
Subject: [PATCH 1/5] [ValueTracking] Add missing check for two-value PN
recurrance matching
When InstTy is a type like IntrinsicInst which can have a variable number of
arguments, we can encounter a case where Opetaion will have fewer than two
arguments and error at the getOperand() calls.
---
llvm/lib/Analysis/ValueTracking.cpp | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 1e70228905c33..b142fc6cc1334 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -9147,7 +9147,8 @@ static bool matchTwoInputRecurrence(const PHINode *PN, InstTy *&Inst,
return false;
for (unsigned I = 0; I != 2; ++I) {
- if (auto *Operation = dyn_cast<InstTy>(PN->getIncomingValue(I))) {
+ if (auto *Operation = dyn_cast<InstTy>(PN->getIncomingValue(I));
+ Operation && Operation->getNumOperands() == 2) {
Value *LHS = Operation->getOperand(0);
Value *RHS = Operation->getOperand(1);
if (LHS != PN && RHS != PN)
>From 8aa5b69737c2245975a8da324b8eb5fb4e78121d Mon Sep 17 00:00:00 2001
From: Ivan Radanov Ivanov <iivanov at nvidia.com>
Date: Fri, 8 Aug 2025 05:53:55 -0700
Subject: [PATCH 2/5] Add test
---
llvm/unittests/Analysis/ValueTrackingTest.cpp | 31 +++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
index 6af20065213ac..56b13af5ce9b6 100644
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -1310,6 +1310,37 @@ TEST_F(ValueTrackingTest, MatchBinaryIntrinsicRecurrenceNegativeFSHR) {
EXPECT_FALSE(matchSimpleBinaryIntrinsicRecurrence(II, PN, Init, OtherOp));
}
+TEST_F(ValueTrackingTest, MatchBinaryIntrinsicRecurrenceNonTwoOperand) {
+ auto M = parseModule(R"(
+ declare noundef i32 @llvm.nvvm.read.ptx.sreg.nctaid.x()
+ declare i32 @llvm.umin.i32(i32, i32)
+
+ define void @foo(i32 %arg) {
+ bb:
+ br i1 false, label %bb1, label %bb2
+
+ bb1: ; preds = %bb
+ br label %bb3
+
+ bb2: ; preds = %bb
+ %i = tail call noundef i32 @llvm.nvvm.read.ptx.sreg.nctaid.x()
+ br label %bb3
+
+ bb3: ; preds = %bb2, %bb1
+ %i4 = phi i32 [ 0, %bb1 ], [ %i, %bb2 ]
+ %i6 = tail call noundef i32 @llvm.umin.i32(i32 %i4, i32 %arg)
+ ret void
+ }
+ )");
+
+ auto *F = M->getFunction("foo");
+ auto *II = &cast<IntrinsicInst>(findInstructionByName(F, "i6"));
+ PHINode *PN;
+ Value *Init, *OtherOp;
+ // Check that it does not crash (see PR #152700)
+ EXPECT_FALSE(matchSimpleBinaryIntrinsicRecurrence(II, PN, Init, OtherOp));
+}
+
TEST_F(ComputeKnownBitsTest, ComputeKnownBits) {
parseAssembly(
"define i32 @test(i32 %a, i32 %b) {\n"
>From ab28b457c6a8b8acb464cd831d0bceb2df2b5ce8 Mon Sep 17 00:00:00 2001
From: Ivan Radanov Ivanov <iivanov at nvidia.com>
Date: Fri, 8 Aug 2025 06:01:04 -0700
Subject: [PATCH 3/5] Actually check >= operands
---
llvm/lib/Analysis/ValueTracking.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index b142fc6cc1334..b0e4b009f3501 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -9148,7 +9148,7 @@ static bool matchTwoInputRecurrence(const PHINode *PN, InstTy *&Inst,
for (unsigned I = 0; I != 2; ++I) {
if (auto *Operation = dyn_cast<InstTy>(PN->getIncomingValue(I));
- Operation && Operation->getNumOperands() == 2) {
+ Operation && Operation->getNumOperands() >= 2) {
Value *LHS = Operation->getOperand(0);
Value *RHS = Operation->getOperand(1);
if (LHS != PN && RHS != PN)
>From 8eef384ffb9212517638acdc1cae5a7f1c9349aa Mon Sep 17 00:00:00 2001
From: "Ivan R. Ivanov" <ivanov.i.aa at m.titech.ac.jp>
Date: Fri, 8 Aug 2025 15:43:34 +0200
Subject: [PATCH 4/5] Update llvm/unittests/Analysis/ValueTrackingTest.cpp
Co-authored-by: Antonio Frighetto <me at antoniofrighetto.com>
---
llvm/unittests/Analysis/ValueTrackingTest.cpp | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)
diff --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
index 56b13af5ce9b6..077925c9d1fba 100644
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -1316,18 +1316,13 @@ TEST_F(ValueTrackingTest, MatchBinaryIntrinsicRecurrenceNonTwoOperand) {
declare i32 @llvm.umin.i32(i32, i32)
define void @foo(i32 %arg) {
- bb:
- br i1 false, label %bb1, label %bb2
-
- bb1: ; preds = %bb
- br label %bb3
-
- bb2: ; preds = %bb
+ entry:
%i = tail call noundef i32 @llvm.nvvm.read.ptx.sreg.nctaid.x()
- br label %bb3
-
- bb3: ; preds = %bb2, %bb1
- %i4 = phi i32 [ 0, %bb1 ], [ %i, %bb2 ]
+ br i1 false, label %bb.1, label %bb.2
+ bb.1: ; preds = %entry
+ br label %bb.2
+ bb.2: ; preds = %bb.2, %bb.1
+ %i4 = phi i32 [ %i, %entry ], [ 0, %bb.1 ]
%i6 = tail call noundef i32 @llvm.umin.i32(i32 %i4, i32 %arg)
ret void
}
>From 2e1cc47a227f758dd242a90ea83fb42f5357c064 Mon Sep 17 00:00:00 2001
From: "Ivan R. Ivanov" <ivanov.i.aa at m.titech.ac.jp>
Date: Fri, 8 Aug 2025 15:53:16 +0200
Subject: [PATCH 5/5] Update llvm/unittests/Analysis/ValueTrackingTest.cpp
Co-authored-by: Antonio Frighetto <me at antoniofrighetto.com>
---
llvm/unittests/Analysis/ValueTrackingTest.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
index 077925c9d1fba..cb1fa4a71ed32 100644
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -1321,7 +1321,7 @@ TEST_F(ValueTrackingTest, MatchBinaryIntrinsicRecurrenceNonTwoOperand) {
br i1 false, label %bb.1, label %bb.2
bb.1: ; preds = %entry
br label %bb.2
- bb.2: ; preds = %bb.2, %bb.1
+ bb.2: ; preds = %entry, %bb.1
%i4 = phi i32 [ %i, %entry ], [ 0, %bb.1 ]
%i6 = tail call noundef i32 @llvm.umin.i32(i32 %i4, i32 %arg)
ret void
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