[PATCH] D73989: AMDGPU: Fix isAlwaysUniform for simple asm SGPR results

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: rampitec, alex-t, nhaehnle, sameerds, kerbowa.
Herald added subscribers: hiraditya, t-tye, tpr, dstuttard, yaxunl, wdng, jvesely, kzhuravl.
Herald added a project: LLVM.

We were handling the case where the result was a struct with an
extracted SGPR component, but not for the simple case.


https://reviews.llvm.org/D73989

Files:
  llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
  llvm/test/Analysis/DivergenceAnalysis/AMDGPU/always_uniform.ll


Index: llvm/test/Analysis/DivergenceAnalysis/AMDGPU/always_uniform.ll
===================================================================
--- llvm/test/Analysis/DivergenceAnalysis/AMDGPU/always_uniform.ll
+++ llvm/test/Analysis/DivergenceAnalysis/AMDGPU/always_uniform.ll
@@ -1,6 +1,6 @@
 ; RUN: opt  -mtriple amdgcn-unknown-amdhsa -analyze -divergence -use-gpu-divergence-analysis %s | FileCheck %s
 
-; CHECK: for function 'readfirstlane':
+; CHECK-LABEL: for function 'readfirstlane':
 define amdgpu_kernel void @readfirstlane() {
   %id.x = call i32 @llvm.amdgcn.workitem.id.x()
 ; CHECK: DIVERGENT:  %id.x = call i32 @llvm.amdgcn.workitem.id.x()
@@ -9,20 +9,42 @@
   ret void
 }
 
-; CHECK: for function 'icmp':
+; CHECK-LABEL: for function 'icmp':
 define amdgpu_kernel void @icmp(i32 inreg %x) {
 ; CHECK-NOT: DIVERGENT:  %icmp = call i64 @llvm.amdgcn.icmp.i32
   %icmp = call i64 @llvm.amdgcn.icmp.i32(i32 %x, i32 0, i32 33)
   ret void
 }
 
-; CHECK: for function 'fcmp':
+; CHECK-LABEL: for function 'fcmp':
 define amdgpu_kernel void @fcmp(float inreg %x, float inreg %y) {
 ; CHECK-NOT: DIVERGENT:  %fcmp = call i64 @llvm.amdgcn.fcmp.i32
   %fcmp = call i64 @llvm.amdgcn.fcmp.i32(float %x, float %y, i32 33)
   ret void
 }
 
+; SGPR asm outputs are uniform regardless of the input operands.
+; CHECK-LABEL: for function 'asm_sgpr':
+; CHECK: DIVERGENT: i32 %divergent
+; CHECK-NOT: DIVERGENT
+define i32 @asm_sgpr(i32 %divergent) {
+  %sgpr = call i32 asm "; def $0, $1","=s,v"(i32 %divergent)
+  ret i32 %sgpr
+}
+
+; CHECK-LABEL: Printing analysis 'Legacy Divergence Analysis' for function 'asm_mixed_sgpr_vgpr':
+; CHECK: DIVERGENT: %asm = call { i32, i32 } asm "; def $0, $1, $2", "=s,=v,v"(i32 %divergent)
+; CHECK-NEXT: {{^[ \t]+}}%sgpr = extractvalue { i32, i32 } %asm, 0
+; CHECK-NEXT: DIVERGENT:       %vgpr = extractvalue { i32, i32 } %asm, 1
+define void @asm_mixed_sgpr_vgpr(i32 %divergent) {
+  %asm = call { i32, i32 } asm "; def $0, $1, $2","=s,=v,v"(i32 %divergent)
+  %sgpr = extractvalue { i32, i32 } %asm, 0
+  %vgpr = extractvalue { i32, i32 } %asm, 1
+  store i32 %sgpr, i32 addrspace(1)* undef
+  store i32 %vgpr, i32 addrspace(1)* undef
+  ret void
+}
+
 declare i32 @llvm.amdgcn.workitem.id.x() #0
 declare i32 @llvm.amdgcn.readfirstlane(i32) #0
 declare i64 @llvm.amdgcn.icmp.i32(i32, i32, i32) #1
Index: llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
@@ -710,6 +710,12 @@
     }
   }
 
+  if (const CallInst *CI = dyn_cast<CallInst>(V)) {
+    if (isa<InlineAsm>(CI->getCalledValue()))
+      return !isInlineAsmSourceOfDivergence(CI);
+    return false;
+  }
+
   const ExtractValueInst *ExtValue = dyn_cast<ExtractValueInst>(V);
   if (!ExtValue)
     return false;


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