[llvm] r337869 - [X86] Change multiply by 26 to use two multiplies by 5 and an add instead of multiply by 3 and 9 and a subtract.
Craig Topper via llvm-commits
llvm-commits at lists.llvm.org
Tue Jul 24 16:44:13 PDT 2018
Author: ctopper
Date: Tue Jul 24 16:44:12 2018
New Revision: 337869
URL: http://llvm.org/viewvc/llvm-project?rev=337869&view=rev
Log:
[X86] Change multiply by 26 to use two multiplies by 5 and an add instead of multiply by 3 and 9 and a subtract.
Same number of operations, but ending in an add is friendlier due to it being commutable.
Modified:
llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
llvm/trunk/test/CodeGen/X86/mul-constant-i16.ll
llvm/trunk/test/CodeGen/X86/mul-constant-i32.ll
llvm/trunk/test/CodeGen/X86/mul-constant-i64.ll
llvm/trunk/test/CodeGen/X86/mul-constant-result.ll
Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=337869&r1=337868&r2=337869&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Tue Jul 24 16:44:12 2018
@@ -33698,10 +33698,10 @@ static SDValue combineMulSpecial(uint64_
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_
// 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();
}
Modified: llvm/trunk/test/CodeGen/X86/mul-constant-i16.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/mul-constant-i16.ll?rev=337869&r1=337868&r2=337869&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/mul-constant-i16.ll (original)
+++ llvm/trunk/test/CodeGen/X86/mul-constant-i16.ll Tue Jul 24 16:44:12 2018
@@ -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
Modified: llvm/trunk/test/CodeGen/X86/mul-constant-i32.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/mul-constant-i32.ll?rev=337869&r1=337868&r2=337869&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/mul-constant-i32.ll (original)
+++ llvm/trunk/test/CodeGen/X86/mul-constant-i32.ll Tue Jul 24 16:44:12 2018
@@ -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:
Modified: llvm/trunk/test/CodeGen/X86/mul-constant-i64.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/mul-constant-i64.ll?rev=337869&r1=337868&r2=337869&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/mul-constant-i64.ll (original)
+++ llvm/trunk/test/CodeGen/X86/mul-constant-i64.ll Tue Jul 24 16:44:12 2018
@@ -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:
Modified: llvm/trunk/test/CodeGen/X86/mul-constant-result.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/mul-constant-result.ll?rev=337869&r1=337868&r2=337869&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/mul-constant-result.ll (original)
+++ llvm/trunk/test/CodeGen/X86/mul-constant-result.ll Tue Jul 24 16:44:12 2018
@@ -193,10 +193,14 @@ define i32 @mult(i32, i32) local_unnamed
; 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
; 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
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