[clang] [llvm] [IR] Drop parameter attributes (PR #195516)
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Sun May 3 05:55:46 PDT 2026
llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-ir
Author: Yingwei Zheng (dtcxzyw)
<details>
<summary>Changes</summary>
Previously `dropPoisonGeneratingReturnAttributes` only considers poison-generating attributes on return values. However, it is not enough as shown in https://github.com/dtcxzyw/llvm-opt-benchmark-nightly/pull/245/files.
This patch also drops parameter attributes, as `dropUBImplyingAttrsAndMetadata` does.
IR diff shows this patch doesn't block existing transformations: https://github.com/dtcxzyw/llvm-opt-benchmark-nightly/pull/246
Compile-time impact looks neutral: https://llvm-compile-time-tracker.com/compare.php?from=d184d9ad0e9f7f34f05d88b7245e7a9a248b245b&to=cdc17034e313657bfd87936e01fa21abd55e184a&stat=instructions:u
---
Full diff: https://github.com/llvm/llvm-project/pull/195516.diff
5 Files Affected:
- (modified) clang/test/Headers/__clang_hip_math.hip (+3-2)
- (modified) llvm/include/llvm/IR/Instruction.h (+7-8)
- (modified) llvm/lib/IR/Instruction.cpp (+16-8)
- (modified) llvm/lib/IR/Operator.cpp (+1-1)
- (modified) llvm/test/Transforms/InstCombine/ispow2.ll (+2-2)
``````````diff
diff --git a/clang/test/Headers/__clang_hip_math.hip b/clang/test/Headers/__clang_hip_math.hip
index 3c15336584501..600a786a5e5ea 100644
--- a/clang/test/Headers/__clang_hip_math.hip
+++ b/clang/test/Headers/__clang_hip_math.hip
@@ -712,6 +712,7 @@ extern "C" __device__ float test_asinhf(float x) {
return asinhf(x);
}
+//
// DEFAULT-LABEL: define dso_local noundef double @test_asinh(
// DEFAULT-SAME: double noundef [[X:%.*]]) local_unnamed_addr #[[ATTR5]] {
// DEFAULT-NEXT: [[ENTRY:.*:]]
@@ -2455,7 +2456,7 @@ extern "C" __device__ double test_fmod(double x, double y) {
// DEFAULT-NEXT: [[TMP2:%.*]] = extractvalue { float, i32 } [[TMP0]], 0
// DEFAULT-NEXT: ret float [[TMP2]]
//
-// FINITEONLY-LABEL: define dso_local noundef nofpclass(nan inf) float @test_frexpf(
+// FINITEONLY-LABEL: define dso_local nofpclass(nan inf) float @test_frexpf(
// FINITEONLY-SAME: float noundef nofpclass(nan inf) [[X:%.*]], ptr noundef writeonly captures(none) initializes((0, 4)) [[Y:%.*]]) local_unnamed_addr #[[ATTR7:[0-9]+]] {
// FINITEONLY-NEXT: [[ENTRY:.*:]]
// FINITEONLY-NEXT: [[TMP0:%.*]] = tail call { float, i32 } @llvm.frexp.f32.i32(float nofpclass(nan inf) [[X]])
@@ -2504,7 +2505,7 @@ extern "C" __device__ float test_frexpf(float x, int* y) {
// DEFAULT-NEXT: [[TMP2:%.*]] = extractvalue { double, i32 } [[TMP0]], 0
// DEFAULT-NEXT: ret double [[TMP2]]
//
-// FINITEONLY-LABEL: define dso_local noundef nofpclass(nan inf) double @test_frexp(
+// FINITEONLY-LABEL: define dso_local nofpclass(nan inf) double @test_frexp(
// FINITEONLY-SAME: double noundef nofpclass(nan inf) [[X:%.*]], ptr noundef writeonly captures(none) initializes((0, 4)) [[Y:%.*]]) local_unnamed_addr #[[ATTR7]] {
// FINITEONLY-NEXT: [[ENTRY:.*:]]
// FINITEONLY-NEXT: [[TMP0:%.*]] = tail call { double, i32 } @llvm.frexp.f64.i32(double nofpclass(nan inf) [[X]])
diff --git a/llvm/include/llvm/IR/Instruction.h b/llvm/include/llvm/IR/Instruction.h
index 0b57ad4d0a379..0e6c122a4e2ef 100644
--- a/llvm/include/llvm/IR/Instruction.h
+++ b/llvm/include/llvm/IR/Instruction.h
@@ -588,23 +588,22 @@ class Instruction : public User,
LLVM_ABI void dropPoisonGeneratingMetadata();
/// Return true if this instruction has poison-generating attribute.
- LLVM_ABI bool hasPoisonGeneratingReturnAttributes() const LLVM_READONLY;
+ LLVM_ABI bool hasPoisonGeneratingAttributes() const LLVM_READONLY;
- /// Drops return attributes that may generate poison.
- LLVM_ABI void dropPoisonGeneratingReturnAttributes();
+ /// Drops attributes that may generate poison.
+ LLVM_ABI void dropPoisonGeneratingAttributes();
/// Return true if this instruction has poison-generating flags,
- /// return attributes or metadata.
+ /// attributes or metadata.
bool hasPoisonGeneratingAnnotations() const {
- return hasPoisonGeneratingFlags() ||
- hasPoisonGeneratingReturnAttributes() ||
+ return hasPoisonGeneratingFlags() || hasPoisonGeneratingAttributes() ||
hasPoisonGeneratingMetadata();
}
- /// Drops flags, return attributes and metadata that may generate poison.
+ /// Drops flags, attributes and metadata that may generate poison.
void dropPoisonGeneratingAnnotations() {
dropPoisonGeneratingFlags();
- dropPoisonGeneratingReturnAttributes();
+ dropPoisonGeneratingAttributes();
dropPoisonGeneratingMetadata();
}
diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index 1932ff72b0a35..b002832ec0624 100644
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -533,18 +533,24 @@ void Instruction::dropPoisonGeneratingMetadata() {
eraseMetadata(ID);
}
-bool Instruction::hasPoisonGeneratingReturnAttributes() const {
+bool Instruction::hasPoisonGeneratingAttributes() const {
if (const auto *CB = dyn_cast<CallBase>(this)) {
- AttributeSet RetAttrs = CB->getAttributes().getRetAttrs();
- return RetAttrs.hasAttribute(Attribute::Range) ||
- RetAttrs.hasAttribute(Attribute::Alignment) ||
- RetAttrs.hasAttribute(Attribute::NonNull) ||
- RetAttrs.hasAttribute(Attribute::NoFPClass);
+ auto HasPoisonGeneratingAttributes = [](AttributeSet Attrs) {
+ return Attrs.hasAttribute(Attribute::Range) ||
+ Attrs.hasAttribute(Attribute::Alignment) ||
+ Attrs.hasAttribute(Attribute::NonNull) ||
+ Attrs.hasAttribute(Attribute::NoFPClass);
+ };
+ if (HasPoisonGeneratingAttributes(CB->getRetAttributes()))
+ return true;
+ for (unsigned ArgNo = 0; ArgNo < CB->arg_size(); ArgNo++)
+ if (HasPoisonGeneratingAttributes(CB->getParamAttributes(ArgNo)))
+ return true;
}
return false;
}
-void Instruction::dropPoisonGeneratingReturnAttributes() {
+void Instruction::dropPoisonGeneratingAttributes() {
if (auto *CB = dyn_cast<CallBase>(this)) {
AttributeMask AM;
AM.addAttribute(Attribute::Range);
@@ -552,8 +558,10 @@ void Instruction::dropPoisonGeneratingReturnAttributes() {
AM.addAttribute(Attribute::NonNull);
AM.addAttribute(Attribute::NoFPClass);
CB->removeRetAttrs(AM);
+ for (unsigned ArgNo = 0; ArgNo < CB->arg_size(); ArgNo++)
+ CB->removeParamAttrs(ArgNo, AM);
}
- assert(!hasPoisonGeneratingReturnAttributes() && "must be kept in sync");
+ assert(!hasPoisonGeneratingAttributes() && "must be kept in sync");
}
void Instruction::dropUBImplyingAttrsAndUnknownMetadata(
diff --git a/llvm/lib/IR/Operator.cpp b/llvm/lib/IR/Operator.cpp
index bd92a32142ebc..aa6c739cee665 100644
--- a/llvm/lib/IR/Operator.cpp
+++ b/llvm/lib/IR/Operator.cpp
@@ -75,7 +75,7 @@ bool Operator::hasPoisonGeneratingAnnotations() const {
if (hasPoisonGeneratingFlags())
return true;
auto *I = dyn_cast<Instruction>(this);
- return I && (I->hasPoisonGeneratingReturnAttributes() ||
+ return I && (I->hasPoisonGeneratingAttributes() ||
I->hasPoisonGeneratingMetadata());
}
diff --git a/llvm/test/Transforms/InstCombine/ispow2.ll b/llvm/test/Transforms/InstCombine/ispow2.ll
index df697e686d986..be8d89d246843 100644
--- a/llvm/test/Transforms/InstCombine/ispow2.ll
+++ b/llvm/test/Transforms/InstCombine/ispow2.ll
@@ -1553,7 +1553,7 @@ define i1 @is_power2_or_zero_with_range(i32 %x) {
; CHECK-NEXT: [[RES:%.*]] = icmp samesign ult i32 [[CTPOP]], 2
; CHECK-NEXT: ret i1 [[RES]]
;
- %ctpop = call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 %x)
+ %ctpop = call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 range(i32 1, 0) %x)
%cmp = icmp eq i32 %ctpop, 1
%notzero = icmp eq i32 %x, 0
%res = select i1 %notzero, i1 true, i1 %cmp
@@ -1566,7 +1566,7 @@ define i1 @is_power2_or_zero_inv_with_range(i32 %x) {
; CHECK-NEXT: [[RES:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT: ret i1 [[RES]]
;
- %ctpop = call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 %x)
+ %ctpop = call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 range(i32 1, 0) %x)
%cmp = icmp ne i32 %ctpop, 1
%notzero = icmp ne i32 %x, 0
%res = select i1 %notzero, i1 %cmp, i1 false
``````````
</details>
https://github.com/llvm/llvm-project/pull/195516
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