diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 25 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2011-05-28-swapmulsub.ll | 45 |
2 files changed, 15 insertions, 55 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index b860440f60..94b619b203 100644 --- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -136,26 +136,19 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { } } - // (Y - X) * (-(2**n)) -> (X - Y) * (2**n), for positive nonzero n - // (Y + const) * (-(2**n)) -> (-constY) * (2**n), for positive nonzero n - // The "* (2**n)" thus becomes a potential shifting opportunity. + // (1 - X) * (-2) -> (x - 1) * 2, for all positive nonzero powers of 2 + // The "* 2" thus becomes a potential shifting opportunity. { const APInt & Val = CI->getValue(); const APInt &PosVal = Val.abs(); if (Val.isNegative() && PosVal.isPowerOf2()) { - Value *X = 0, *Y = 0; - ConstantInt *C1 = 0; - if (Op0->hasOneUse() && - (match(Op0, m_Sub(m_Value(Y), m_Value(X)))) || - (match(Op0, m_Add(m_Value(Y), m_ConstantInt(C1))))) { - Value *Sub; - if (C1) // Matched ADD of constant, negate both operands: - Sub = Builder->CreateSub(Builder->CreateNeg(C1), Y, "subc"); - else // Matched SUB, swap operands: - Sub = Builder->CreateSub(X, Y, "suba"); - return - BinaryOperator::CreateMul(Sub, - ConstantInt::get(X->getType(), PosVal)); + Value *X = 0; + if (match(Op0, m_Sub(m_One(), m_Value(X)))) { + // ConstantInt::get(Op0->getType(), 2); + Value *Sub = Builder->CreateSub(X, ConstantInt::get(X->getType(), 1), + "dec1"); + return BinaryOperator::CreateMul(Sub, ConstantInt::get(X->getType(), + PosVal)); } } } diff --git a/test/Transforms/InstCombine/2011-05-28-swapmulsub.ll b/test/Transforms/InstCombine/2011-05-28-swapmulsub.ll index b096d1f952..e4417ef96a 100644 --- a/test/Transforms/InstCombine/2011-05-28-swapmulsub.ll +++ b/test/Transforms/InstCombine/2011-05-28-swapmulsub.ll @@ -2,14 +2,18 @@ ; RUN: opt -S -instcombine < %s | FileCheck %s target triple = "x86_64-apple-macosx10.6.6" -define zeroext i16 @foo1(i32 %on_off) nounwind uwtable ssp { +define zeroext i16 @foo(i32 %on_off, i16* %puls) nounwind uwtable ssp { entry: %on_off.addr = alloca i32, align 4 + %puls.addr = alloca i16*, align 8 %a = alloca i32, align 4 store i32 %on_off, i32* %on_off.addr, align 4 + store i16* %puls, i16** %puls.addr, align 8 %tmp = load i32* %on_off.addr, align 4 +; CHECK-NOT: sub +; CHECK-NOT: mul +; (1 - %tmp) * (-2) -> (%tmp - 1) * 2 %sub = sub i32 1, %tmp -; CHECK-NOT: mul i32 %mul = mul i32 %sub, -2 ; CHECK: shl ; CHECK-NEXT: add @@ -18,40 +22,3 @@ entry: %conv = trunc i32 %tmp1 to i16 ret i16 %conv } - -define zeroext i16 @foo2(i32 %on_off, i32 %q) nounwind uwtable ssp { -entry: - %on_off.addr = alloca i32, align 4 - %q.addr = alloca i32, align 4 - %a = alloca i32, align 4 - store i32 %on_off, i32* %on_off.addr, align 4 - store i32 %q, i32* %q.addr, align 4 - %tmp = load i32* %q.addr, align 4 - %tmp1 = load i32* %on_off.addr, align 4 - %sub = sub i32 %tmp, %tmp1 -; CHECK-NOT: mul i32 - %mul = mul i32 %sub, -4 -; CHECK: sub i32 -; CHECK-NEXT: shl - store i32 %mul, i32* %a, align 4 - %tmp2 = load i32* %a, align 4 - %conv = trunc i32 %tmp2 to i16 - ret i16 %conv -} - -define zeroext i16 @foo3(i32 %on_off) nounwind uwtable ssp { -entry: - %on_off.addr = alloca i32, align 4 - %a = alloca i32, align 4 - store i32 %on_off, i32* %on_off.addr, align 4 - %tmp = load i32* %on_off.addr, align 4 - %sub = sub i32 7, %tmp -; CHECK-NOT: mul i32 - %mul = mul i32 %sub, -4 -; CHECK: shl -; CHECK-NEXT: add - store i32 %mul, i32* %a, align 4 - %tmp1 = load i32* %a, align 4 - %conv = trunc i32 %tmp1 to i16 - ret i16 %conv -} |