[llvm] [IR] Mark vector intrinsics speculatable, willreturn (PR #162334)
Ramkumar Ramachandra via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 7 10:49:35 PDT 2025
https://github.com/artagnon created https://github.com/llvm/llvm-project/pull/162334
The vector intrinsics in questions have no undefined behavior, and have no other effect besides returning the result, and do return a result: they should hence be marked speculatable and willreturn.
At the moment, there are no optimizations that are enabled by these attributes, and the patch is mainly just documentation.
>From 6d733fd84dace33b2dbe6c5166c2f84dbfa39b88 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Tue, 7 Oct 2025 16:45:24 +0100
Subject: [PATCH] [IR] Mark vector intrinsics speculatable, willreturn
The vector intrinsics in questions have no undefined behavior, and have
no other effect besides returning the result, and do return a result:
they should hence be marked speculatable and willreturn.
At the moment, there are no optimizations that are enabled by these
attributes, and the patch is mainly just documentation.
---
llvm/include/llvm/IR/Intrinsics.td | 46 ++++++++++++++-----
.../RISCV/veclib-function-calls.ll | 2 +-
.../AArch64/expand-exp.ll | 1 -
3 files changed, 35 insertions(+), 14 deletions(-)
diff --git a/llvm/include/llvm/IR/Intrinsics.td b/llvm/include/llvm/IR/Intrinsics.td
index 96da698538314..fef80a88bfbc2 100644
--- a/llvm/include/llvm/IR/Intrinsics.td
+++ b/llvm/include/llvm/IR/Intrinsics.td
@@ -2422,12 +2422,12 @@ def int_loop_dependence_war_mask:
def int_get_active_lane_mask:
DefaultAttrsIntrinsic<[llvm_anyvector_ty],
[llvm_anyint_ty, LLVMMatchType<1>],
- [IntrNoMem]>;
+ [IntrNoMem, IntrSpeculatable, IntrWillReturn]>;
def int_experimental_get_vector_length:
DefaultAttrsIntrinsic<[llvm_i32_ty],
[llvm_anyint_ty, llvm_i32_ty, llvm_i1_ty],
- [IntrNoMem,
+ [IntrNoMem, IntrSpeculatable, IntrWillReturn,
ImmArg<ArgIndex<1>>, ImmArg<ArgIndex<2>>]>;
def int_experimental_cttz_elts:
@@ -2614,7 +2614,7 @@ def int_memset_element_unordered_atomic
//===------------------------ Reduction Intrinsics ------------------------===//
//
-let IntrProperties = [IntrNoMem, IntrSpeculatable] in {
+let IntrProperties = [IntrNoMem, IntrSpeculatable, IntrWillReturn] in {
def int_vector_reduce_fadd : DefaultAttrsIntrinsic<[LLVMVectorElementType<0>],
[LLVMVectorElementType<0>,
@@ -2753,41 +2753,63 @@ def int_preserve_static_offset : DefaultAttrsIntrinsic<[llvm_ptr_ty],
def int_vector_reverse : DefaultAttrsIntrinsic<[llvm_anyvector_ty],
[LLVMMatchType<0>],
- [IntrNoMem]>;
+ [IntrNoMem,
+ IntrSpeculatable,
+ IntrWillReturn]>;
def int_vector_splice : DefaultAttrsIntrinsic<[llvm_anyvector_ty],
[LLVMMatchType<0>,
LLVMMatchType<0>,
llvm_i32_ty],
- [IntrNoMem, ImmArg<ArgIndex<2>>]>;
+ [IntrNoMem,
+ IntrSpeculatable,
+ IntrWillReturn,
+ ImmArg<ArgIndex<2>>]>;
//===---------- Intrinsics to query properties of scalable vectors --------===//
-def int_vscale : DefaultAttrsIntrinsic<[llvm_anyint_ty], [], [IntrNoMem]>;
+def int_vscale : DefaultAttrsIntrinsic<[llvm_anyint_ty],
+ [],
+ [IntrNoMem,
+ IntrSpeculatable,
+ IntrWillReturn]>;
//===---------- Intrinsics to perform subvector insertion/extraction ------===//
def int_vector_insert : DefaultAttrsIntrinsic<[llvm_anyvector_ty],
[LLVMMatchType<0>, llvm_anyvector_ty, llvm_i64_ty],
- [IntrNoMem, IntrSpeculatable, ImmArg<ArgIndex<2>>]>;
+ [IntrNoMem,
+ IntrSpeculatable,
+ IntrWillReturn,
+ ImmArg<ArgIndex<2>>]>;
def int_vector_extract : DefaultAttrsIntrinsic<[llvm_anyvector_ty],
[llvm_anyvector_ty, llvm_i64_ty],
- [IntrNoMem, IntrSpeculatable, ImmArg<ArgIndex<1>>]>;
+ [IntrNoMem,
+ IntrSpeculatable,
+ IntrWillReturn,
+ ImmArg<ArgIndex<1>>]>;
foreach n = 2...8 in {
def int_vector_interleave#n : DefaultAttrsIntrinsic<[llvm_anyvector_ty],
!listsplat(LLVMOneNthElementsVectorType<0, n>, n),
- [IntrNoMem]>;
+ [IntrNoMem,
+ IntrSpeculatable,
+ IntrWillReturn]>;
def int_vector_deinterleave#n : DefaultAttrsIntrinsic<!listsplat(LLVMOneNthElementsVectorType<0, n>, n),
[llvm_anyvector_ty],
- [IntrNoMem]>;
+ [IntrNoMem,
+ IntrSpeculatable,
+ IntrWillReturn]>;
}
//===-------------- Intrinsics to perform partial reduction ---------------===//
def int_vector_partial_reduce_add : DefaultAttrsIntrinsic<[LLVMMatchType<0>],
- [llvm_anyvector_ty, llvm_anyvector_ty],
- [IntrNoMem]>;
+ [llvm_anyvector_ty,
+ llvm_anyvector_ty],
+ [IntrNoMem,
+ IntrSpeculatable,
+ IntrWillReturn]>;
//===----------------- Pointer Authentication Intrinsics ------------------===//
//
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/veclib-function-calls.ll b/llvm/test/Transforms/LoopVectorize/RISCV/veclib-function-calls.ll
index d73900dcd0bea..83b494a1be0d3 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/veclib-function-calls.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/veclib-function-calls.ll
@@ -2288,7 +2288,7 @@ define void @tgamma_f32(ptr noalias %in.ptr, ptr noalias %out.ptr) {
}
;.
; CHECK: attributes #[[ATTR0]] = { "target-features"="+v" }
-; CHECK: attributes #[[ATTR1:[0-9]+]] = { nocallback nofree nosync nounwind willreturn memory(none) }
+; CHECK: attributes #[[ATTR1:[0-9]+]] = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
; CHECK: attributes #[[ATTR2]] = { "vector-function-abi-variant"="_ZGVrNxv_acos(Sleef_acosdx_u10rvvm2)" }
; CHECK: attributes #[[ATTR3]] = { "vector-function-abi-variant"="_ZGVrNxv_acosf(Sleef_acosfx_u10rvvm2)" }
; CHECK: attributes #[[ATTR4]] = { "vector-function-abi-variant"="_ZGVrNxv_acosh(Sleef_acoshdx_u10rvvm2)" }
diff --git a/llvm/test/Transforms/PreISelIntrinsicLowering/AArch64/expand-exp.ll b/llvm/test/Transforms/PreISelIntrinsicLowering/AArch64/expand-exp.ll
index 9acc6d6601292..09f583f9242d5 100644
--- a/llvm/test/Transforms/PreISelIntrinsicLowering/AArch64/expand-exp.ll
+++ b/llvm/test/Transforms/PreISelIntrinsicLowering/AArch64/expand-exp.ll
@@ -39,5 +39,4 @@ declare <4 x float> @llvm.exp.v4f32(<4 x float>) #0
declare <vscale x 4 x float> @llvm.exp.nxv4f32(<vscale x 4 x float>) #0
; CHECK: attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
-; CHECK-NEXT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(none) }
attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
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