[PATCH] D37019: Add select simplifications

[Michael Berg via Phabricator via llvm-commits]

mcberg2017 updated this revision to Diff 112241.
mcberg2017 added a comment.

Updated for fast math flags


https://reviews.llvm.org/D37019

Files:
  lib/Transforms/InstCombine/InstCombineAddSub.cpp
  lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
  test/Transforms/InstCombine/select_arithmetic.ll


Index: test/Transforms/InstCombine/select_arithmetic.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/select_arithmetic.ll
@@ -0,0 +1,33 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+define float @test1(i1 zeroext) #0 {
+  %2 = select i1 %0, float 5.000000e+00, float 6.000000e+00
+  %3 = select i1 %0, float 1.000000e+00, float 9.000000e+00
+  %4 = fadd float %2, %3
+  ret float %4
+; CHECK-LABEL: @test1(
+; CHECK: %2 = select i1 %0, float 6.000000e+00, float 1.500000e+01
+; CHECK-NOT: fadd
+; CHECK: ret float %2
+}
+
+define float @test2(i1 zeroext) #0 {
+  %2 = select i1 %0, float 5.000000e+00, float 6.000000e+00
+  %3 = select i1 %0, float 1.000000e+00, float 9.000000e+00
+  %4 = fmul float %2, %3
+  ret float %4
+; CHECK-LABEL: @test2(
+; CHECK: %2 = select i1 %0, float 5.000000e+00, float 5.400000e+01
+; CHECK-NOT: fmul
+; CHECK: ret float %2
+}
+
+attributes #0 = { noinline nounwind ssp uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="penryn" "target-features"="+cx16,+fxsr,+mmx,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0}
+!llvm.ident = !{!1}
+
+!0 = !{i32 1, !"PIC Level", i32 2}
+!1 = !{!"Apple LLVM version 9.0.0 (clang-900.0.32)"}
Index: lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -603,6 +603,13 @@
                                   SQ.getWithInstruction(&I)))
     return replaceInstUsesWith(I, V);
 
+  if (Value *V = SimplifyUsingDistributiveLaws(I)) {
+    if (Instruction *NewInstr = dyn_cast<Instruction>(V))
+      NewInstr->setFastMathFlags(I.getFastMathFlags());
+
+    return replaceInstUsesWith(I, V);
+  }
+
   bool AllowReassociate = I.hasUnsafeAlgebra();
 
   // Simplify mul instructions with a constant RHS.
Index: lib/Transforms/InstCombine/InstCombineAddSub.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1309,6 +1309,14 @@
                                   SQ.getWithInstruction(&I)))
     return replaceInstUsesWith(I, V);
 
+  // (A*B)+(A*C) -> A*(B+C) etc
+  if (Value *V = SimplifyUsingDistributiveLaws(I)) {
+    if (Instruction *NewInstr = dyn_cast<Instruction>(V))
+      NewInstr->setFastMathFlags(I.getFastMathFlags()); 
+
+    return replaceInstUsesWith(I, V);
+  }
+
   if (isa<Constant>(RHS))
     if (Instruction *FoldedFAdd = foldOpWithConstantIntoOperand(I))
       return FoldedFAdd;
@@ -1724,6 +1732,13 @@
                                   SQ.getWithInstruction(&I)))
     return replaceInstUsesWith(I, V);
 
+  // (A*B)-(A*C) -> A*(B-C) etc
+  if (Value *V = SimplifyUsingDistributiveLaws(I)) {
+    if (Instruction *NewInstr = dyn_cast<Instruction>(V))
+      NewInstr->setFastMathFlags(I.getFastMathFlags()); 
+    return replaceInstUsesWith(I, V);
+  }
+
   // fsub nsz 0, X ==> fsub nsz -0.0, X
   if (I.getFastMathFlags().noSignedZeros() && match(Op0, m_Zero())) {
     // Subtraction from -0.0 is the canonical form of fneg.


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