diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp | 15 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/shift.ll | 14 |
2 files changed, 10 insertions, 19 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp index db6e4951a7a..2891edd4502 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp @@ -763,25 +763,14 @@ Instruction *InstCombiner::visitShl(BinaryOperator &I) { unsigned ShAmt = ShAmtAPInt->getZExtValue(); unsigned BitWidth = Ty->getScalarSizeInBits(); + // shl (zext X), ShAmt --> zext (shl X, ShAmt) + // This is only valid if X would have zeros shifted out. Value *X; if (match(Op0, m_OneUse(m_ZExt(m_Value(X))))) { unsigned SrcWidth = X->getType()->getScalarSizeInBits(); - // shl (zext X), ShAmt --> zext (shl X, ShAmt) - // This is only valid if X would have zeros shifted out. if (ShAmt < SrcWidth && MaskedValueIsZero(X, APInt::getHighBitsSet(SrcWidth, ShAmt), 0, &I)) return new ZExtInst(Builder.CreateShl(X, ShAmt), Ty); - - // shl (zext (mul MulOp, C2)), ShAmt --> mul (zext MulOp), (C2 << ShAmt) - // This is valid if the high bits of the wider multiply are shifted out. - Value *MulOp; - const APInt *C2; - if (ShAmt >= (BitWidth - SrcWidth) && - match(X, m_Mul(m_Value(MulOp), m_APInt(C2)))) { - Value *Zext = Builder.CreateZExt(MulOp, Ty); - Constant *NewMulC = ConstantInt::get(Ty, C2->zext(BitWidth).shl(ShAmt)); - return BinaryOperator::CreateMul(Zext, NewMulC); - } } // (X >> C) << C --> X & (-1 << C) diff --git a/llvm/test/Transforms/InstCombine/shift.ll b/llvm/test/Transforms/InstCombine/shift.ll index 4a09b15d82b..a0e6bbe33ee 100644 --- a/llvm/test/Transforms/InstCombine/shift.ll +++ b/llvm/test/Transforms/InstCombine/shift.ll @@ -1223,8 +1223,9 @@ define <2 x i64> @shl_zext_splat_vec(<2 x i32> %t) { define i64 @shl_zext_mul(i32 %t) { ; CHECK-LABEL: @shl_zext_mul( -; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[T:%.*]] to i64 -; CHECK-NEXT: [[SHL:%.*]] = mul i64 [[TMP1]], 72057589742960640 +; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[T:%.*]], 16777215 +; CHECK-NEXT: [[EXT:%.*]] = zext i32 [[MUL]] to i64 +; CHECK-NEXT: [[SHL:%.*]] = shl nuw i64 [[EXT]], 32 ; CHECK-NEXT: ret i64 [[SHL]] ; %mul = mul i32 %t, 16777215 @@ -1235,8 +1236,9 @@ define i64 @shl_zext_mul(i32 %t) { define <3 x i17> @shl_zext_mul_splat(<3 x i5> %t) { ; CHECK-LABEL: @shl_zext_mul_splat( -; CHECK-NEXT: [[TMP1:%.*]] = zext <3 x i5> [[T:%.*]] to <3 x i17> -; CHECK-NEXT: [[SHL:%.*]] = mul <3 x i17> [[TMP1]], <i17 53248, i17 53248, i17 53248> +; CHECK-NEXT: [[MUL:%.*]] = mul <3 x i5> [[T:%.*]], <i5 13, i5 13, i5 13> +; CHECK-NEXT: [[EXT:%.*]] = zext <3 x i5> [[MUL]] to <3 x i17> +; CHECK-NEXT: [[SHL:%.*]] = shl nuw <3 x i17> [[EXT]], <i17 12, i17 12, i17 12> ; CHECK-NEXT: ret <3 x i17> [[SHL]] ; %mul = mul <3 x i5> %t, <i5 13, i5 13, i5 13> @@ -1279,8 +1281,8 @@ define i64 @shl_zext_mul_extra_use2(i32 %t) { ; CHECK-LABEL: @shl_zext_mul_extra_use2( ; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[T:%.*]], 16777215 ; CHECK-NEXT: call void @use_i32(i32 [[MUL]]) -; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[T]] to i64 -; CHECK-NEXT: [[SHL:%.*]] = mul i64 [[TMP1]], 72057589742960640 +; CHECK-NEXT: [[EXT:%.*]] = zext i32 [[MUL]] to i64 +; CHECK-NEXT: [[SHL:%.*]] = shl nuw i64 [[EXT]], 32 ; CHECK-NEXT: ret i64 [[SHL]] ; %mul = mul i32 %t, 16777215 |
