diff options
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 22 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/imul.ll | 23 |
2 files changed, 23 insertions, 22 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index ef8a6d68395..12f6d409a60 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -33922,14 +33922,20 @@ static SDValue combineMul(SDNode *N, SelectionDAG &DAG, DAG.getNode(ISD::SHL, DL, VT, N->getOperand(0), DAG.getConstant(Log2_64(NumSign * SignMulAmt - 1), DL, MVT::i8))); + // To negate, subtract the number from zero + if (SignMulAmt < 0) + NewMul = DAG.getNode(ISD::SUB, DL, VT, + DAG.getConstant(0, DL, VT), NewMul); } else if (IsPowerOf2_64MinusOne) { // (mul x, 2^N - 1) => (sub (shl x, N), x) - NewMul = DAG.getNode( - ISD::SUB, DL, VT, - DAG.getNode(ISD::SHL, DL, VT, N->getOperand(0), - DAG.getConstant(Log2_64(NumSign * SignMulAmt + 1), DL, - MVT::i8)), - N->getOperand(0)); + NewMul = DAG.getNode(ISD::SHL, DL, VT, N->getOperand(0), + DAG.getConstant(Log2_64(NumSign * SignMulAmt + 1), + DL, MVT::i8)); + // To negate, reverse the operands of the subtract. + if (SignMulAmt < 0) + NewMul = DAG.getNode(ISD::SUB, DL, VT, N->getOperand(0), NewMul); + else + NewMul = DAG.getNode(ISD::SUB, DL, VT, NewMul, N->getOperand(0)); } else if (IsPowerOf2_64MinusTwo && NumSign == 1) { // (mul x, 2^N - 1) => (sub (shl x, N), x) NewMul = DAG.getNode(ISD::SHL, DL, VT, N->getOperand(0), @@ -33938,10 +33944,6 @@ static SDValue combineMul(SDNode *N, SelectionDAG &DAG, NewMul = DAG.getNode(ISD::SUB, DL, VT, NewMul, N->getOperand(0)); NewMul = DAG.getNode(ISD::SUB, DL, VT, NewMul, N->getOperand(0)); } - // To negate, subtract the number from zero - if (NewMul && NumSign == -1) - NewMul = - DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT), NewMul); } } diff --git a/llvm/test/CodeGen/X86/imul.ll b/llvm/test/CodeGen/X86/imul.ll index 761484c069b..14f15143b95 100644 --- a/llvm/test/CodeGen/X86/imul.ll +++ b/llvm/test/CodeGen/X86/imul.ll @@ -324,17 +324,16 @@ define i32 @test1(i32 %a) { ; X64: # %bb.0: # %entry ; X64-NEXT: movl %edi, %eax ; X64-NEXT: shll $5, %eax -; X64-NEXT: subl %edi, %eax -; X64-NEXT: negl %eax +; X64-NEXT: subl %eax, %edi +; X64-NEXT: movl %edi, %eax ; X64-NEXT: retq ; ; X86-LABEL: test1: ; X86: # %bb.0: # %entry -; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx -; X86-NEXT: movl %ecx, %eax -; X86-NEXT: shll $5, %eax +; X86-NEXT: movl {{[0-9]+}}(%esp), %eax +; X86-NEXT: movl %eax, %ecx +; X86-NEXT: shll $5, %ecx ; X86-NEXT: subl %ecx, %eax -; X86-NEXT: negl %eax ; X86-NEXT: retl entry: %tmp3 = mul i32 %a, -31 @@ -414,8 +413,8 @@ define i64 @test5(i64 %a) { ; X64: # %bb.0: # %entry ; X64-NEXT: movq %rdi, %rax ; X64-NEXT: shlq $5, %rax -; X64-NEXT: subq %rdi, %rax -; X64-NEXT: negq %rax +; X64-NEXT: subq %rax, %rdi +; X64-NEXT: movq %rdi, %rax ; X64-NEXT: retq ; ; X86-LABEL: test5: @@ -424,15 +423,15 @@ define i64 @test5(i64 %a) { ; X86-NEXT: .cfi_def_cfa_offset 8 ; X86-NEXT: .cfi_offset %esi, -8 ; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx -; X86-NEXT: movl {{[0-9]+}}(%esp), %eax -; X86-NEXT: movl %eax, %esi -; X86-NEXT: shll $5, %esi +; X86-NEXT: movl {{[0-9]+}}(%esp), %esi +; X86-NEXT: movl %esi, %eax +; X86-NEXT: shll $5, %eax ; X86-NEXT: subl %eax, %esi ; X86-NEXT: movl $-31, %edx ; X86-NEXT: movl %ecx, %eax ; X86-NEXT: mull %edx ; X86-NEXT: subl %ecx, %edx -; X86-NEXT: subl %esi, %edx +; X86-NEXT: addl %esi, %edx ; X86-NEXT: popl %esi ; X86-NEXT: .cfi_def_cfa_offset 4 ; X86-NEXT: retl |
