[llvm] f5296df - [FPEnv][AMDGPU] Correct AMDGPUSimplifyLibCalls handling of strictfp attribute. (#86705)

[via llvm-commits]

Author: Kevin P. Neal
Date: 2024-03-27T10:20:00-04:00
New Revision: f5296df97c6bdc6cb658691e5863fdbf336d4430

URL: https://github.com/llvm/llvm-project/commit/f5296df97c6bdc6cb658691e5863fdbf336d4430
DIFF: https://github.com/llvm/llvm-project/commit/f5296df97c6bdc6cb658691e5863fdbf336d4430.diff

LOG: [FPEnv][AMDGPU] Correct AMDGPUSimplifyLibCalls handling of strictfp attribute. (#86705)

The AMDGPUSimplifyLibCalls pass was lowering function calls with the
strictfp attribute to sequences that included function calls incorrectly
lacking the attribute. This patch corrects that.

The pass now also emits the correct constrained fp call instead of
normal FP instructions when in a function with the strictfp attribute.
Replacing non-constrained calls with constrained calls when required
is still on the IRBuilder's TODO list.

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
    llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pown.ll
    llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-rootn.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp b/llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
index 84b4ccc1ae7ba7..5aa35becd842c3 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
@@ -657,6 +657,8 @@ bool AMDGPULibCalls::fold(CallInst *CI) {
     return true;
 
   IRBuilder<> B(CI);
+  if (CI->isStrictFP())
+    B.setIsFPConstrained(true);
 
   if (FPMathOperator *FPOp = dyn_cast<FPMathOperator>(CI)) {
     // Under unsafe-math, evaluate calls if possible.

diff  --git a/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pown.ll b/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pown.ll
index 942f459ea6b8ca..8ddaf243db92c4 100644
--- a/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pown.ll
+++ b/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pown.ll
@@ -808,7 +808,7 @@ define float @test_pown_fast_f32_nobuiltin(float %x, i32 %y) {
 ; CHECK-LABEL: define float @test_pown_fast_f32_nobuiltin
 ; CHECK-SAME: (float [[X:%.*]], i32 [[Y:%.*]]) {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[CALL:%.*]] = tail call fast float @_Z4pownfi(float [[X]], i32 [[Y]]) #[[ATTR3:[0-9]+]]
+; CHECK-NEXT:    [[CALL:%.*]] = tail call fast float @_Z4pownfi(float [[X]], i32 [[Y]]) #[[ATTR4:[0-9]+]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
 entry:
@@ -820,11 +820,11 @@ define float @test_pown_fast_f32_strictfp(float %x, i32 %y) #1 {
 ; CHECK-LABEL: define float @test_pown_fast_f32_strictfp
 ; CHECK-SAME: (float [[X:%.*]], i32 [[Y:%.*]]) #[[ATTR0:[0-9]+]] {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[__FABS:%.*]] = call fast float @llvm.fabs.f32(float [[X]])
-; CHECK-NEXT:    [[__LOG2:%.*]] = call fast float @llvm.log2.f32(float [[__FABS]])
-; CHECK-NEXT:    [[POWNI2F:%.*]] = sitofp i32 [[Y]] to float
-; CHECK-NEXT:    [[__YLOGX:%.*]] = fmul fast float [[__LOG2]], [[POWNI2F]]
-; CHECK-NEXT:    [[__EXP2:%.*]] = call fast float @llvm.exp2.f32(float [[__YLOGX]])
+; CHECK-NEXT:    [[__FABS:%.*]] = call fast float @llvm.fabs.f32(float [[X]]) #[[ATTR0]]
+; CHECK-NEXT:    [[__LOG2:%.*]] = call fast float @llvm.log2.f32(float [[__FABS]]) #[[ATTR0]]
+; CHECK-NEXT:    [[POWNI2F:%.*]] = call fast float @llvm.experimental.constrained.sitofp.f32.i32(i32 [[Y]], metadata !"round.dynamic", metadata !"fpexcept.strict") #[[ATTR0]]
+; CHECK-NEXT:    [[__YLOGX:%.*]] = call fast float @llvm.experimental.constrained.fmul.f32(float [[POWNI2F]], float [[__LOG2]], metadata !"round.dynamic", metadata !"fpexcept.strict") #[[ATTR0]]
+; CHECK-NEXT:    [[__EXP2:%.*]] = call fast float @llvm.exp2.f32(float [[__YLOGX]]) #[[ATTR0]]
 ; CHECK-NEXT:    [[__YEVEN:%.*]] = shl i32 [[Y]], 31
 ; CHECK-NEXT:    [[TMP0:%.*]] = bitcast float [[X]] to i32
 ; CHECK-NEXT:    [[__POW_SIGN:%.*]] = and i32 [[__YEVEN]], [[TMP0]]

diff  --git a/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-rootn.ll b/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-rootn.ll
index 2ffa647d1869a5..2e64a3456c2427 100644
--- a/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-rootn.ll
+++ b/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-rootn.ll
@@ -896,7 +896,7 @@ define float @test_rootn_f32__y_neg2__strictfp(float %x) #1 {
 ; CHECK-LABEL: define float @test_rootn_f32__y_neg2__strictfp(
 ; CHECK-SAME: float [[X:%.*]]) #[[ATTR0]] {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[__ROOTN2RSQRT:%.*]] = call float @_Z5rsqrtf(float [[X]])
+; CHECK-NEXT:    [[__ROOTN2RSQRT:%.*]] = call float @_Z5rsqrtf(float [[X]]) #[[ATTR0]]
 ; CHECK-NEXT:    ret float [[__ROOTN2RSQRT]]
 ;
 entry: