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[X86] Change multiply by 26 to use two multiplies by 5 and an add instead of multiply by 3 and 9 and a subtract.

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Same number of operations, but ending in an add is friendlier due to it being commutable.

llvm-svn: 337869
This commit is contained in:
Craig Topper 2018-07-24 23:44:12 +00:00
parent 8b02a7fb90
commit 05023f522e
5 changed files with 41 additions and 37 deletions
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14
lib/Target/X86/X86ISelLowering.cpp
View File

@ -33698,10 +33698,10 @@ static SDValue combineMulSpecial(uint64_t MulAmt, SDNode *N, SelectionDAG &DAG,
return Result;
};
auto combineMulMulAddOrSub = [&](bool isAdd) {
auto combineMulMulAddOrSub = [&](int Mul1, int Mul2, bool isAdd) {
SDValue Result = DAG.getNode(X86ISD::MUL_IMM, DL, VT, N->getOperand(0),
DAG.getConstant(9, DL, VT));
Result = DAG.getNode(ISD::MUL, DL, VT, Result, DAG.getConstant(3, DL, VT));
DAG.getConstant(Mul1, DL, VT));
Result = DAG.getNode(ISD::MUL, DL, VT, Result, DAG.getConstant(Mul2, DL, VT));
Result = DAG.getNode(isAdd ? ISD::ADD : ISD::SUB, DL, VT, Result,
N->getOperand(0));
return Result;
@ -33730,15 +33730,15 @@ static SDValue combineMulSpecial(uint64_t MulAmt, SDNode *N, SelectionDAG &DAG,
// mul x, 23 => sub ((shl (mul x, 3), 3), x)
return combineMulShlAddOrSub(3, 3, /*isAdd*/ false);
case 26:
// mul x, 26 => sub ((mul (mul x, 9), 3), x)
return combineMulMulAddOrSub(/*isAdd*/ false);
// mul x, 26 => add ((mul (mul x, 5), 5), x)
return combineMulMulAddOrSub(5, 5, /*isAdd*/ true);
case 28:
// mul x, 28 => add ((mul (mul x, 9), 3), x)
return combineMulMulAddOrSub(/*isAdd*/ true);
return combineMulMulAddOrSub(9, 3, /*isAdd*/ true);
case 29:
// mul x, 29 => add (add ((mul (mul x, 9), 3), x), x)
return DAG.getNode(ISD::ADD, DL, VT, N->getOperand(0),
combineMulMulAddOrSub(/*isAdd*/ true));
combineMulMulAddOrSub(9, 3, /*isAdd*/ true));
}
return SDValue();
}

12
test/CodeGen/X86/mul-constant-i16.ll
View File

@ -494,18 +494,18 @@ define i16 @test_mul_by_26(i16 %x) {
; X86-LABEL: test_mul_by_26:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: leal (%ecx,%ecx,8), %eax
; X86-NEXT: leal (%eax,%eax,2), %eax
; X86-NEXT: subl %ecx, %eax
; X86-NEXT: leal (%ecx,%ecx,4), %eax
; X86-NEXT: leal (%eax,%eax,4), %eax
; X86-NEXT: addl %ecx, %eax
; X86-NEXT: # kill: def $ax killed $ax killed $eax
; X86-NEXT: retl
;
; X64-LABEL: test_mul_by_26:
; X64: # %bb.0:
; X64-NEXT: # kill: def $edi killed $edi def $rdi
; X64-NEXT: leal (%rdi,%rdi,8), %eax
; X64-NEXT: leal (%rax,%rax,2), %eax
; X64-NEXT: subl %edi, %eax
; X64-NEXT: leal (%rdi,%rdi,4), %eax
; X64-NEXT: leal (%rax,%rax,4), %eax
; X64-NEXT: addl %edi, %eax
; X64-NEXT: # kill: def $ax killed $ax killed $eax
; X64-NEXT: retq
%mul = mul nsw i16 %x, 26

18
test/CodeGen/X86/mul-constant-i32.ll
View File

@ -1304,25 +1304,25 @@ define i32 @test_mul_by_26(i32 %x) {
; X86-LABEL: test_mul_by_26:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: leal (%ecx,%ecx,8), %eax
; X86-NEXT: leal (%eax,%eax,2), %eax
; X86-NEXT: subl %ecx, %eax
; X86-NEXT: leal (%ecx,%ecx,4), %eax
; X86-NEXT: leal (%eax,%eax,4), %eax
; X86-NEXT: addl %ecx, %eax
; X86-NEXT: retl
;
; X64-HSW-LABEL: test_mul_by_26:
; X64-HSW: # %bb.0:
; X64-HSW-NEXT: # kill: def $edi killed $edi def $rdi
; X64-HSW-NEXT: leal (%rdi,%rdi,8), %eax # sched: [1:0.50]
; X64-HSW-NEXT: leal (%rax,%rax,2), %eax # sched: [1:0.50]
; X64-HSW-NEXT: subl %edi, %eax # sched: [1:0.25]
; X64-HSW-NEXT: leal (%rdi,%rdi,4), %eax # sched: [1:0.50]
; X64-HSW-NEXT: leal (%rax,%rax,4), %eax # sched: [1:0.50]
; X64-HSW-NEXT: addl %edi, %eax # sched: [1:0.25]
; X64-HSW-NEXT: retq # sched: [7:1.00]
;
; X64-JAG-LABEL: test_mul_by_26:
; X64-JAG: # %bb.0:
; X64-JAG-NEXT: # kill: def $edi killed $edi def $rdi
; X64-JAG-NEXT: leal (%rdi,%rdi,8), %eax # sched: [2:1.00]
; X64-JAG-NEXT: leal (%rax,%rax,2), %eax # sched: [2:1.00]
; X64-JAG-NEXT: subl %edi, %eax # sched: [1:0.50]
; X64-JAG-NEXT: leal (%rdi,%rdi,4), %eax # sched: [2:1.00]
; X64-JAG-NEXT: leal (%rax,%rax,4), %eax # sched: [2:1.00]
; X64-JAG-NEXT: addl %edi, %eax # sched: [1:0.50]
; X64-JAG-NEXT: retq # sched: [4:1.00]
;
; X86-NOOPT-LABEL: test_mul_by_26:

18
test/CodeGen/X86/mul-constant-i64.ll
View File

@ -1358,9 +1358,9 @@ define i64 @test_mul_by_26(i64 %x) {
; X86-LABEL: test_mul_by_26:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; X86-NEXT: leal (%eax,%eax,8), %ecx
; X86-NEXT: leal (%ecx,%ecx,2), %ecx
; X86-NEXT: subl %eax, %ecx
; X86-NEXT: leal (%eax,%eax,4), %ecx
; X86-NEXT: leal (%ecx,%ecx,4), %ecx
; X86-NEXT: addl %eax, %ecx
; X86-NEXT: movl $26, %eax
; X86-NEXT: mull {{[0-9]+}}(%esp)
; X86-NEXT: addl %ecx, %edx
@ -1368,16 +1368,16 @@ define i64 @test_mul_by_26(i64 %x) {
;
; X64-HSW-LABEL: test_mul_by_26:
; X64-HSW: # %bb.0:
; X64-HSW-NEXT: leaq (%rdi,%rdi,8), %rax # sched: [1:0.50]
; X64-HSW-NEXT: leaq (%rax,%rax,2), %rax # sched: [1:0.50]
; X64-HSW-NEXT: subq %rdi, %rax # sched: [1:0.25]
; X64-HSW-NEXT: leaq (%rdi,%rdi,4), %rax # sched: [1:0.50]
; X64-HSW-NEXT: leaq (%rax,%rax,4), %rax # sched: [1:0.50]
; X64-HSW-NEXT: addq %rdi, %rax # sched: [1:0.25]
; X64-HSW-NEXT: retq # sched: [7:1.00]
;
; X64-JAG-LABEL: test_mul_by_26:
; X64-JAG: # %bb.0:
; X64-JAG-NEXT: leaq (%rdi,%rdi,8), %rax # sched: [2:1.00]
; X64-JAG-NEXT: leaq (%rax,%rax,2), %rax # sched: [2:1.00]
; X64-JAG-NEXT: subq %rdi, %rax # sched: [1:0.50]
; X64-JAG-NEXT: leaq (%rdi,%rdi,4), %rax # sched: [2:1.00]
; X64-JAG-NEXT: leaq (%rax,%rax,4), %rax # sched: [2:1.00]
; X64-JAG-NEXT: addq %rdi, %rax # sched: [1:0.50]
; X64-JAG-NEXT: retq # sched: [4:1.00]
;
; X86-NOOPT-LABEL: test_mul_by_26:

16
test/CodeGen/X86/mul-constant-result.ll
View File

@ -193,10 +193,14 @@ define i32 @mult(i32, i32) local_unnamed_addr #0 {
; X86-NEXT: retl
; X86-NEXT: .LBB0_32:
; X86-NEXT: .cfi_def_cfa_offset 8
; X86-NEXT: leal (%eax,%eax,8), %ecx
; X86-NEXT: leal (%ecx,%ecx,2), %ecx
; X86-NEXT: jmp .LBB0_12
; X86-NEXT: leal (%eax,%eax,4), %ecx
; X86-NEXT: leal (%ecx,%ecx,4), %ecx
; X86-NEXT: addl %ecx, %eax
; X86-NEXT: popl %esi
; X86-NEXT: .cfi_def_cfa_offset 4
; X86-NEXT: retl
; X86-NEXT: .LBB0_33:
; X86-NEXT: .cfi_def_cfa_offset 8
; X86-NEXT: leal (%eax,%eax,8), %eax
; X86-NEXT: leal (%eax,%eax,2), %eax
; X86-NEXT: popl %esi
@ -369,9 +373,9 @@ define i32 @mult(i32, i32) local_unnamed_addr #0 {
; X64-HSW-NEXT: # kill: def $eax killed $eax killed $rax
; X64-HSW-NEXT: retq
; X64-HSW-NEXT: .LBB0_29:
; X64-HSW-NEXT: leal (%rax,%rax,8), %ecx
; X64-HSW-NEXT: leal (%rcx,%rcx,2), %ecx
; X64-HSW-NEXT: jmp .LBB0_8
; X64-HSW-NEXT: leal (%rax,%rax,4), %ecx
; X64-HSW-NEXT: leal (%rcx,%rcx,4), %ecx
; X64-HSW-NEXT: jmp .LBB0_20
; X64-HSW-NEXT: .LBB0_30:
; X64-HSW-NEXT: leal (%rax,%rax,8), %eax
; X64-HSW-NEXT: leal (%rax,%rax,2), %eax