[PATCH] D158994: AMDGPU: Cleanup check for integral exponents in pow folds

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: AMDGPU, rampitec, jmmartinez.
Herald added subscribers: foad, kerbowa, hiraditya, tpr, dstuttard, yaxunl, jvesely, kzhuravl.
Herald added a project: All.
arsenm requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.

Also improves undef handling


https://reviews.llvm.org/D158994

Files:
  llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
  llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pow.ll


Index: llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pow.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pow.ll
+++ llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pow.ll
@@ -1784,8 +1784,10 @@
 define <2 x float> @test_pow_afn_v2f32_nnan_ninf__y_poison(<2 x float> %x) {
 ; CHECK-LABEL: define <2 x float> @test_pow_afn_v2f32_nnan_ninf__y_poison
 ; CHECK-SAME: (<2 x float> [[X:%.*]]) {
-; CHECK-NEXT:    [[POW:%.*]] = tail call nnan ninf afn <2 x float> @_Z3powDv2_fS_(<2 x float> [[X]], <2 x float> poison)
-; CHECK-NEXT:    ret <2 x float> [[POW]]
+; CHECK-NEXT:    [[__FABS:%.*]] = call nnan ninf afn <2 x float> @llvm.fabs.v2f32(<2 x float> [[X]])
+; CHECK-NEXT:    [[__LOG2:%.*]] = call nnan ninf afn <2 x float> @_Z4log2Dv2_f(<2 x float> [[__FABS]])
+; CHECK-NEXT:    [[__EXP2:%.*]] = call nnan ninf afn <2 x float> @_Z4exp2Dv2_f(<2 x float> poison)
+; CHECK-NEXT:    ret <2 x float> poison
 ;
   %pow = tail call afn nnan ninf <2 x float> @_Z3powDv2_fS_(<2 x float> %x, <2 x float> poison)
   ret <2 x float> %pow
Index: llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
@@ -567,6 +567,29 @@
   return true;
 }
 
+static bool isKnownIntegral(const Value *V) {
+  if (isa<UndefValue>(V))
+    return true;
+
+  if (const ConstantFP *CF = dyn_cast<ConstantFP>(V))
+    return CF->getValueAPF().isInteger();
+
+  if (const ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(V)) {
+    for (unsigned i = 0, e = CDV->getNumElements(); i != e; ++i) {
+      Constant *ConstElt = CDV->getElementAsConstant(i);
+      if (isa<UndefValue>(ConstElt))
+        continue;
+      const ConstantFP *CFP = dyn_cast<ConstantFP>(ConstElt);
+      if (!CFP || !CFP->getValue().isInteger())
+        return false;
+    }
+
+    return true;
+  }
+
+  return false;
+}
+
 // This function returns false if no change; return true otherwise.
 bool AMDGPULibCalls::fold(CallInst *CI) {
   Function *Callee = CI->getCalledFunction();
@@ -990,25 +1013,8 @@
   if (needcopysign && (FInfo.getId() == AMDGPULibFunc::EI_POW)) {
     // We cannot handle corner cases for a general pow() function, give up
     // unless y is a constant integral value. Then proceed as if it were pown.
-    if (getVecSize(FInfo) == 1) {
-      if (const ConstantFP *CF = dyn_cast<ConstantFP>(opr1)) {
-        double y = (getArgType(FInfo) == AMDGPULibFunc::F32)
-                   ? (double)CF->getValueAPF().convertToFloat()
-                   : CF->getValueAPF().convertToDouble();
-        if (y != (double)(int64_t)y)
-          return false;
-      } else
-        return false;
-    } else {
-      if (const ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(opr1)) {
-        for (int i=0; i < getVecSize(FInfo); ++i) {
-          double y = CDV->getElementAsAPFloat(i).convertToDouble();
-          if (y != (double)(int64_t)y)
-            return false;
-        }
-      } else
-        return false;
-    }
+    if (!isKnownIntegral(opr1))
+      return false;
   }
 
   Value *nval;


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