[PATCH] D155309: [NewGVN] Canonicalize expressions for commutative intrinsics

[Manuel Brito via Phabricator via llvm-commits]

ManuelJBrito created this revision.
ManuelJBrito added reviewers: asbirlea, nlopes, fhahn.
Herald added subscribers: kmitropoulou, StephenFan, hiraditya.
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ManuelJBrito requested review of this revision.
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This addresses https://github.com/llvm/llvm-project/issues/46753.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D155309

Files:
  llvm/lib/Transforms/Scalar/NewGVN.cpp
  llvm/test/Transforms/NewGVN/commute.ll


Index: llvm/test/Transforms/NewGVN/commute.ll
===================================================================
--- llvm/test/Transforms/NewGVN/commute.ll
+++ llvm/test/Transforms/NewGVN/commute.ll
@@ -34,8 +34,7 @@
 define void @intrinsic(i32 %x, i32 %y) {
 ; CHECK-LABEL: @intrinsic(
 ; CHECK-NEXT:    [[M1:%.*]] = call i32 @llvm.smax.i32(i32 [[X:%.*]], i32 [[Y:%.*]])
-; CHECK-NEXT:    [[M2:%.*]] = call i32 @llvm.smax.i32(i32 [[Y]], i32 [[X]])
-; CHECK-NEXT:    call void @use(i32 [[M1]], i32 [[M2]])
+; CHECK-NEXT:    call void @use(i32 [[M1]], i32 [[M1]])
 ; CHECK-NEXT:    ret void
 ;
   %m1 = call i32 @llvm.smax.i32(i32 %x, i32 %y)
@@ -49,10 +48,7 @@
 
 define i16 @intrinsic_3_args(i16 %x, i16 %y) {
 ; CHECK-LABEL: @intrinsic_3_args(
-; CHECK-NEXT:    [[M1:%.*]] = call i16 @llvm.smul.fix.i16(i16 [[X:%.*]], i16 [[Y:%.*]], i32 1)
-; CHECK-NEXT:    [[M2:%.*]] = call i16 @llvm.smul.fix.i16(i16 [[Y]], i16 [[X]], i32 1)
-; CHECK-NEXT:    [[R:%.*]] = sub i16 [[M1]], [[M2]]
-; CHECK-NEXT:    ret i16 [[R]]
+; CHECK-NEXT:    ret i16 0
 ;
   %m1 = call i16 @llvm.smul.fix.i16(i16 %x, i16 %y, i32 1)
   %m2 = call i16 @llvm.smul.fix.i16(i16 %y, i16 %x, i32 1)
@@ -78,8 +74,7 @@
 define float @fma(float %x, float %y) {
 ; CHECK-LABEL: @fma(
 ; CHECK-NEXT:    [[M1:%.*]] = call float @llvm.fma.f32(float [[X:%.*]], float [[Y:%.*]], float 1.000000e+00)
-; CHECK-NEXT:    [[M2:%.*]] = call float @llvm.fma.f32(float [[Y]], float [[X]], float 1.000000e+00)
-; CHECK-NEXT:    [[R:%.*]] = fdiv nnan float [[M1]], [[M2]]
+; CHECK-NEXT:    [[R:%.*]] = fdiv nnan float [[M1]], [[M1]]
 ; CHECK-NEXT:    ret float [[R]]
 ;
   %m1 = call float @llvm.fma.f32(float %x, float %y, float 1.0)
@@ -87,3 +82,18 @@
   %r = fdiv nnan float %m1, %m2
   ret float %r
 }
+
+declare i16 @llvm.sdiv.fix.i16(i16, i16, i32)
+
+define i16 @intrinsic_3_args_not_commutative(i16 %x, i16 %y) {
+; CHECK-LABEL: @intrinsic_3_args_not_commutative(
+; CHECK-NEXT:    [[M1:%.*]] = call i16 @llvm.sdiv.fix.i16(i16 [[X:%.*]], i16 [[Y:%.*]], i32 1)
+; CHECK-NEXT:    [[M2:%.*]] = call i16 @llvm.sdiv.fix.i16(i16 [[Y]], i16 [[X]], i32 1)
+; CHECK-NEXT:    [[R:%.*]] = sub i16 [[M1]], [[M2]]
+; CHECK-NEXT:    ret i16 [[R]]
+;
+  %m1 = call i16 @llvm.sdiv.fix.i16(i16 %x, i16 %y, i32 1)
+  %m2 = call i16 @llvm.sdiv.fix.i16(i16 %y, i16 %x, i32 1)
+  %r = sub i16 %m1, %m2
+  ret i16 %r
+}
Index: llvm/lib/Transforms/Scalar/NewGVN.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/NewGVN.cpp
+++ llvm/lib/Transforms/Scalar/NewGVN.cpp
@@ -1274,10 +1274,17 @@
 const CallExpression *
 NewGVN::createCallExpression(CallInst *CI, const MemoryAccess *MA) const {
   // FIXME: Add operand bundles for calls.
-  // FIXME: Allow commutative matching for intrinsics.
   auto *E =
       new (ExpressionAllocator) CallExpression(CI->getNumOperands(), CI, MA);
   setBasicExpressionInfo(CI, E);
+  if (CI->isCommutative()) {
+    // Ensure that commutative intrinsics that only differ by a permutation
+    // of their operands get the same value number by sorting the operand value
+    // numbers.
+    assert(CI->getNumOperands() >= 2 && "Unsupported commutative intrinsic!");
+    if (shouldSwapOperands(E->getOperand(0), E->getOperand(1)))
+      E->swapOperands(0, 1);
+  }
   return E;
 }
 


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