Index: lib/Transforms/InstCombine/InstCombineShifts.cpp =================================================================== --- lib/Transforms/InstCombine/InstCombineShifts.cpp +++ lib/Transforms/InstCombine/InstCombineShifts.cpp @@ -312,35 +312,17 @@ // If this is a bitwise operator or add with a constant RHS we might be able // to pull it through a shift. static bool canShiftBinOpWithConstantRHS(BinaryOperator &Shift, - BinaryOperator *BO, - const APInt &C) { - bool IsValid = true; // Valid only for And, Or Xor, - bool HighBitSet = false; // Transform ifhigh bit of constant set? - + BinaryOperator *BO) { switch (BO->getOpcode()) { - default: IsValid = false; break; // Do not perform transform! + default: + return false; // Do not perform transform! case Instruction::Add: - IsValid = Shift.getOpcode() == Instruction::Shl; - break; + return Shift.getOpcode() == Instruction::Shl; case Instruction::Or: case Instruction::Xor: - HighBitSet = false; - break; case Instruction::And: - HighBitSet = true; - break; + return true; } - - // If this is a signed shift right, and the high bit is modified - // by the logical operation, do not perform the transformation. - // The HighBitSet boolean indicates the value of the high bit of - // the constant which would cause it to be modified for this - // operation. - // - if (IsValid && Shift.getOpcode() == Instruction::AShr) - IsValid = C.isNegative() == HighBitSet; - - return IsValid; } Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, Constant *Op1, @@ -507,7 +489,7 @@ // shift is the only use, we can pull it out of the shift. const APInt *Op0C; if (match(Op0BO->getOperand(1), m_APInt(Op0C))) { - if (canShiftBinOpWithConstantRHS(I, Op0BO, *Op0C)) { + if (canShiftBinOpWithConstantRHS(I, Op0BO)) { Constant *NewRHS = ConstantExpr::get(I.getOpcode(), cast(Op0BO->getOperand(1)), Op1); @@ -551,7 +533,7 @@ const APInt *C; if (!isa(FalseVal) && TBO->getOperand(0) == FalseVal && match(TBO->getOperand(1), m_APInt(C)) && - canShiftBinOpWithConstantRHS(I, TBO, *C)) { + canShiftBinOpWithConstantRHS(I, TBO)) { Constant *NewRHS = ConstantExpr::get(I.getOpcode(), cast(TBO->getOperand(1)), Op1); @@ -570,7 +552,7 @@ const APInt *C; if (!isa(TrueVal) && FBO->getOperand(0) == TrueVal && match(FBO->getOperand(1), m_APInt(C)) && - canShiftBinOpWithConstantRHS(I, FBO, *C)) { + canShiftBinOpWithConstantRHS(I, FBO)) { Constant *NewRHS = ConstantExpr::get(I.getOpcode(), cast(FBO->getOperand(1)), Op1); Index: test/Transforms/InstCombine/pull-binop-through-shift.ll =================================================================== --- test/Transforms/InstCombine/pull-binop-through-shift.ll +++ test/Transforms/InstCombine/pull-binop-through-shift.ll @@ -198,8 +198,8 @@ define i32 @or_signbit_ashr(i32 %x) { ; CHECK-LABEL: @or_signbit_ashr( -; CHECK-NEXT: [[T0:%.*]] = or i32 [[X:%.*]], -65536 -; CHECK-NEXT: [[R:%.*]] = ashr i32 [[T0]], 8 +; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 [[X:%.*]], 8 +; CHECK-NEXT: [[R:%.*]] = or i32 [[TMP1]], -256 ; CHECK-NEXT: ret i32 [[R]] ; %t0 = or i32 %x, 4294901760 ; 0xFFFF0000 @@ -219,8 +219,8 @@ define i32 @xor_signbit_ashr(i32 %x) { ; CHECK-LABEL: @xor_signbit_ashr( -; CHECK-NEXT: [[T0:%.*]] = xor i32 [[X:%.*]], -65536 -; CHECK-NEXT: [[R:%.*]] = ashr i32 [[T0]], 8 +; CHECK-NEXT: [[T0:%.*]] = ashr i32 [[X:%.*]], 8 +; CHECK-NEXT: [[R:%.*]] = xor i32 [[T0]], -256 ; CHECK-NEXT: ret i32 [[R]] ; %t0 = xor i32 %x, 4294901760 ; 0xFFFF0000 Index: test/Transforms/InstCombine/pull-conditional-binop-through-shift.ll =================================================================== --- test/Transforms/InstCombine/pull-conditional-binop-through-shift.ll +++ test/Transforms/InstCombine/pull-conditional-binop-through-shift.ll @@ -221,9 +221,9 @@ } define i32 @and_nosignbit_select_ashr(i32 %x, i1 %cond) { ; CHECK-LABEL: @and_nosignbit_select_ashr( -; CHECK-NEXT: [[T0:%.*]] = and i32 [[X:%.*]], 2147418112 -; CHECK-NEXT: [[T1:%.*]] = select i1 [[COND:%.*]], i32 [[T0]], i32 [[X]] -; CHECK-NEXT: [[R:%.*]] = ashr i32 [[T1]], 8 +; CHECK-NEXT: [[TMP1:%.*]] = ashr i32 [[X:%.*]], 8 +; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], 8388352 +; CHECK-NEXT: [[R:%.*]] = select i1 [[COND:%.*]], i32 [[TMP2]], i32 [[TMP1]] ; CHECK-NEXT: ret i32 [[R]] ; %t0 = and i32 %x, 2147418112 ; 0x7FFF0000 @@ -234,9 +234,9 @@ define i32 @or_signbit_select_ashr(i32 %x, i1 %cond) { ; CHECK-LABEL: @or_signbit_select_ashr( -; CHECK-NEXT: [[T0:%.*]] = or i32 [[X:%.*]], -65536 -; CHECK-NEXT: [[T1:%.*]] = select i1 [[COND:%.*]], i32 [[T0]], i32 [[X]] -; CHECK-NEXT: [[R:%.*]] = ashr i32 [[T1]], 8 +; CHECK-NEXT: [[TMP1:%.*]] = ashr i32 [[X:%.*]], 8 +; CHECK-NEXT: [[TMP2:%.*]] = or i32 [[TMP1]], -256 +; CHECK-NEXT: [[R:%.*]] = select i1 [[COND:%.*]], i32 [[TMP2]], i32 [[TMP1]] ; CHECK-NEXT: ret i32 [[R]] ; %t0 = or i32 %x, 4294901760 ; 0xFFFF0000 @@ -259,9 +259,9 @@ define i32 @xor_signbit_select_ashr(i32 %x, i1 %cond) { ; CHECK-LABEL: @xor_signbit_select_ashr( -; CHECK-NEXT: [[T0:%.*]] = xor i32 [[X:%.*]], -65536 -; CHECK-NEXT: [[T1:%.*]] = select i1 [[COND:%.*]], i32 [[T0]], i32 [[X]] -; CHECK-NEXT: [[R:%.*]] = ashr i32 [[T1]], 8 +; CHECK-NEXT: [[TMP1:%.*]] = ashr i32 [[X:%.*]], 8 +; CHECK-NEXT: [[TMP2:%.*]] = xor i32 [[TMP1]], -256 +; CHECK-NEXT: [[R:%.*]] = select i1 [[COND:%.*]], i32 [[TMP2]], i32 [[TMP1]] ; CHECK-NEXT: ret i32 [[R]] ; %t0 = xor i32 %x, 4294901760 ; 0xFFFF0000 Index: test/Transforms/InstCombine/trunc.ll =================================================================== --- test/Transforms/InstCombine/trunc.ll +++ test/Transforms/InstCombine/trunc.ll @@ -125,8 +125,8 @@ define i32 @trunc_ashr(i32 %X) { ; CHECK-LABEL: @trunc_ashr( -; CHECK-NEXT: [[B:%.*]] = or i32 [[X:%.*]], -2147483648 -; CHECK-NEXT: [[C:%.*]] = ashr i32 [[B]], 8 +; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 [[X:%.*]], 8 +; CHECK-NEXT: [[C:%.*]] = or i32 [[TMP1]], -8388608 ; CHECK-NEXT: ret i32 [[C]] ; %A = zext i32 %X to i36 @@ -138,8 +138,8 @@ define <2 x i32> @trunc_ashr_vec(<2 x i32> %X) { ; CHECK-LABEL: @trunc_ashr_vec( -; CHECK-NEXT: [[B:%.*]] = or <2 x i32> [[X:%.*]], -; CHECK-NEXT: [[C:%.*]] = ashr <2 x i32> [[B]], +; CHECK-NEXT: [[TMP1:%.*]] = lshr <2 x i32> [[X:%.*]], +; CHECK-NEXT: [[C:%.*]] = or <2 x i32> [[TMP1]], ; CHECK-NEXT: ret <2 x i32> [[C]] ; %A = zext <2 x i32> %X to <2 x i36>