[PATCH] D38263: [InstCombine] Gating select arithmetic optimization
Chad Rosier via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 27 10:18:33 PDT 2017
This revision was automatically updated to reflect the committed changes.
Closed by commit rL314320: [InstCombine] Gating select arithmetic optimization. (authored by mcrosier).
Changed prior to commit:
https://reviews.llvm.org/D38263?vs=116702&id=116839#toc
Repository:
rL LLVM
https://reviews.llvm.org/D38263
Files:
llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/select_arithmetic.ll
Index: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -731,17 +731,18 @@
Value *SI = nullptr;
if (match(LHS, m_Select(m_Value(A), m_Value(B), m_Value(C))) &&
match(RHS, m_Select(m_Specific(A), m_Value(D), m_Value(E)))) {
+ bool SelectsHaveOneUse = LHS->hasOneUse() && RHS->hasOneUse();
BuilderTy::FastMathFlagGuard Guard(Builder);
if (isa<FPMathOperator>(&I))
Builder.setFastMathFlags(I.getFastMathFlags());
Value *V1 = SimplifyBinOp(Opcode, C, E, SQ.getWithInstruction(&I));
Value *V2 = SimplifyBinOp(Opcode, B, D, SQ.getWithInstruction(&I));
if (V1 && V2)
SI = Builder.CreateSelect(A, V2, V1);
- else if (V2)
+ else if (V2 && SelectsHaveOneUse)
SI = Builder.CreateSelect(A, V2, Builder.CreateBinOp(Opcode, C, E));
- else if (V1)
+ else if (V1 && SelectsHaveOneUse)
SI = Builder.CreateSelect(A, Builder.CreateBinOp(Opcode, B, D), V1);
if (SI)
Index: llvm/trunk/test/Transforms/InstCombine/select_arithmetic.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/select_arithmetic.ll
+++ llvm/trunk/test/Transforms/InstCombine/select_arithmetic.ll
@@ -3,17 +3,32 @@
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
; Tests folding constants from two similar selects that feed a add
-define float @test1(i1 zeroext %arg) #0 {
+define float @test1a(i1 zeroext %arg) #0 {
%tmp = select i1 %arg, float 5.000000e+00, float 6.000000e+00
%tmp1 = select i1 %arg, float 1.000000e+00, float 9.000000e+00
%tmp2 = fadd float %tmp, %tmp1
ret float %tmp2
-; CHECK-LABEL: @test1(
+; CHECK-LABEL: @test1a(
; CHECK: %tmp2 = select i1 %arg, float 6.000000e+00, float 1.500000e+01
; CHECK-NOT: fadd
; CHECK: ret float %tmp2
}
+; Tests folding multiple expression constants from similar selects that feed a adds
+define float @test1b(i1 zeroext %arg) #0 {
+ %tmp = select i1 %arg, float 5.000000e+00, float 6.000000e+00
+ %tmp1 = select i1 %arg, float 1.000000e+00, float 9.000000e+00
+ %tmp2 = select i1 %arg, float 2.500000e-01, float 4.000000e+00
+ %tmp3 = fadd float %tmp, %tmp1
+ %tmp4 = fadd float %tmp2, %tmp1
+ %tmp5 = fadd float %tmp4, %tmp3
+ ret float %tmp5
+; CHECK-LABEL: @test1b(
+; CHECK: %tmp5 = select i1 %arg, float 7.250000e+00, float 2.800000e+01
+; CHECK-NOT: fadd
+; CHECK: ret float %tmp5
+}
+
; Tests folding constants from two similar selects that feed a sub
define float @test2(i1 zeroext %arg) #0 {
%tmp = select i1 %arg, float 5.000000e+00, float 6.000000e+00
@@ -38,3 +53,32 @@
; CHECK: ret float %tmp2
}
+declare void @use_float(float)
+
+; Tests folding constants if the selects have multiple uses but
+; we can fold away the binary op with a select.
+define float @test4(i1 zeroext %arg) #0 {
+ %tmp = select i1 %arg, float 5.000000e+00, float 6.000000e+00
+ %tmp1 = select i1 %arg, float 1.000000e+00, float 9.000000e+00
+ %tmp2 = fmul float %tmp, %tmp1
+ call void @use_float(float %tmp)
+ ret float %tmp2
+; CHECK-LABEL: @test4(
+; CHECK: select i1 %arg, float 5.000000e+00, float 6.000000e+00
+; CHECK-NEXT: select i1 %arg, float 5.000000e+00, float 5.400000e+01
+; CHECK-NEXT: call void @use_float(float %tmp)
+; CHECK: ret float %tmp2
+}
+
+; Tests not folding constants if we cannot fold away any of the selects.
+define float @test5(i1 zeroext %arg, float %div) {
+ %tmp = select i1 %arg, float %div, float 5.000000e+00
+ %mul = fmul contract float %tmp, %tmp
+ call void @use_float(float %tmp)
+ ret float %mul
+; CHECK-LABEL: @test5(
+; CHECK: [[TMP:%.*]] = select i1 %arg, float %div, float 5.000000e+00
+; CHECK-NEXT: [[MUL:%.*]] = fmul contract float [[TMP]], [[TMP]]
+; CHECK-NOT: fmul contract float %div, %div
+; CHECK: ret float [[MUL]]
+}
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