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[ExpandMemCmp] Properly constant-fold all compares.
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Summary:
This gets rid of duplicated code and diverging behaviour w.r.t.
constants.
Fixes PR45086.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75519
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@legrosbuffle
legrosbuffle committed Mar 9, 2020
1 parent 2ce821c commit 6518b72
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Showing 7 changed files with 101 additions and 137 deletions.
4 changes: 4 additions & 0 deletions llvm/lib/CodeGen/ExpandMemCmp.cpp
View file
Expand Up @@ -23,6 +23,7 @@
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/InitializePasses.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SizeOpts.h"

using namespace llvm;
Expand Down Expand Up @@ -845,6 +846,9 @@ PreservedAnalyses ExpandMemCmpPass::runImpl(
++BBIt;
}
}
if (MadeChanges)
for (BasicBlock &BB : F)
SimplifyInstructionsInBlock(&BB);
return MadeChanges ? PreservedAnalyses::none() : PreservedAnalyses::all();
}

Expand Down
38 changes: 2 additions & 36 deletions llvm/test/CodeGen/PowerPC/memCmpUsedInZeroEqualityComparison.ll
View file
Expand Up @@ -89,28 +89,8 @@ define signext i32 @zeroEqualityTest03(i8* %x, i8* %y) {
; Validate with > 0
define signext i32 @zeroEqualityTest04() {
; CHECK-LABEL: zeroEqualityTest04:
; CHECK: # %bb.0:
; CHECK-NEXT: b .LBB3_2
; CHECK-NEXT: # %bb.1: # %loadbb1
; CHECK: # %bb.0: # %loadbb
; CHECK-NEXT: li 3, 0
; CHECK-NEXT: li 5, 0
; CHECK-NEXT: li 4, 0
; CHECK-NEXT: b .LBB3_4
; CHECK-NEXT: .LBB3_2:
; CHECK-NEXT: li 3, 1
; CHECK-NEXT: li 4, 3
; CHECK-NEXT: sldi 3, 3, 58
; CHECK-NEXT: sldi 4, 4, 56
; CHECK-NEXT: # %bb.3: # %res_block
; CHECK-NEXT: cmpld 3, 4
; CHECK-NEXT: li 3, 1
; CHECK-NEXT: li 4, -1
; CHECK-NEXT: isel 5, 4, 3, 0
; CHECK-NEXT: .LBB3_4: # %endblock
; CHECK-NEXT: extsw 3, 5
; CHECK-NEXT: neg 3, 3
; CHECK-NEXT: rldicl 3, 3, 1, 63
; CHECK-NEXT: xori 3, 3, 1
; CHECK-NEXT: blr
%call = tail call signext i32 @memcmp(i8* bitcast ([4 x i32]* @zeroEqualityTest02.buffer1 to i8*), i8* bitcast ([4 x i32]* @zeroEqualityTest02.buffer2 to i8*), i64 16)
%not.cmp = icmp slt i32 %call, 1
Expand All @@ -121,22 +101,8 @@ define signext i32 @zeroEqualityTest04() {
; Validate with < 0
define signext i32 @zeroEqualityTest05() {
; CHECK-LABEL: zeroEqualityTest05:
; CHECK: # %bb.0:
; CHECK-NEXT: li 3, 0
; CHECK-NEXT: li 4, 0
; CHECK-NEXT: # %bb.1: # %loadbb1
; CHECK: # %bb.0: # %loadbb
; CHECK-NEXT: li 3, 0
; CHECK-NEXT: # %bb.2:
; CHECK-NEXT: lis 3, 768
; CHECK-NEXT: lis 4, 1024
; CHECK-NEXT: # %bb.3: # %res_block
; CHECK-NEXT: cmpld 3, 4
; CHECK-NEXT: li 3, 1
; CHECK-NEXT: li 4, -1
; CHECK-NEXT: isel 3, 4, 3, 0
; CHECK-NEXT: # %bb.4: # %endblock
; CHECK-NEXT: nor 3, 3, 3
; CHECK-NEXT: rlwinm 3, 3, 1, 31, 31
; CHECK-NEXT: blr
%call = tail call signext i32 @memcmp(i8* bitcast ([4 x i32]* @zeroEqualityTest03.buffer1 to i8*), i8* bitcast ([4 x i32]* @zeroEqualityTest03.buffer2 to i8*), i64 16)
%call.lobit = lshr i32 %call, 31
Expand Down
52 changes: 26 additions & 26 deletions llvm/test/CodeGen/X86/memcmp-more-load-pairs.ll
View file
Expand Up @@ -230,7 +230,7 @@ define i1 @length2_eq_nobuiltin_attr(i8* %X, i8* %Y) nounwind {

define i32 @length3(i8* %X, i8* %Y) nounwind {
; X86-LABEL: length3:
; X86: # %bb.0: # %loadbb
; X86: # %bb.0:
; X86-NEXT: pushl %esi
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
Expand All @@ -239,34 +239,34 @@ define i32 @length3(i8* %X, i8* %Y) nounwind {
; X86-NEXT: rolw $8, %dx
; X86-NEXT: rolw $8, %si
; X86-NEXT: cmpw %si, %dx
; X86-NEXT: jne .LBB9_1
; X86-NEXT: # %bb.2: # %loadbb1
; X86-NEXT: jne .LBB9_3
; X86-NEXT: # %bb.1: # %loadbb1
; X86-NEXT: movzbl 2(%eax), %eax
; X86-NEXT: movzbl 2(%ecx), %ecx
; X86-NEXT: subl %ecx, %eax
; X86-NEXT: popl %esi
; X86-NEXT: retl
; X86-NEXT: .LBB9_1: # %res_block
; X86-NEXT: .LBB9_3: # %res_block
; X86-NEXT: setae %al
; X86-NEXT: movzbl %al, %eax
; X86-NEXT: leal -1(%eax,%eax), %eax
; X86-NEXT: popl %esi
; X86-NEXT: retl
;
; X64-LABEL: length3:
; X64: # %bb.0: # %loadbb
; X64: # %bb.0:
; X64-NEXT: movzwl (%rdi), %eax
; X64-NEXT: movzwl (%rsi), %ecx
; X64-NEXT: rolw $8, %ax
; X64-NEXT: rolw $8, %cx
; X64-NEXT: cmpw %cx, %ax
; X64-NEXT: jne .LBB9_1
; X64-NEXT: # %bb.2: # %loadbb1
; X64-NEXT: jne .LBB9_3
; X64-NEXT: # %bb.1: # %loadbb1
; X64-NEXT: movzbl 2(%rdi), %eax
; X64-NEXT: movzbl 2(%rsi), %ecx
; X64-NEXT: subl %ecx, %eax
; X64-NEXT: retq
; X64-NEXT: .LBB9_1: # %res_block
; X64-NEXT: .LBB9_3: # %res_block
; X64-NEXT: setae %al
; X64-NEXT: movzbl %al, %eax
; X64-NEXT: leal -1(%rax,%rax), %eax
Expand Down Expand Up @@ -445,7 +445,7 @@ define i1 @length4_eq_const(i8* %X) nounwind {

define i32 @length5(i8* %X, i8* %Y) nounwind {
; X86-LABEL: length5:
; X86: # %bb.0: # %loadbb
; X86: # %bb.0:
; X86-NEXT: pushl %esi
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
Expand All @@ -454,34 +454,34 @@ define i32 @length5(i8* %X, i8* %Y) nounwind {
; X86-NEXT: bswapl %edx
; X86-NEXT: bswapl %esi
; X86-NEXT: cmpl %esi, %edx
; X86-NEXT: jne .LBB16_1
; X86-NEXT: # %bb.2: # %loadbb1
; X86-NEXT: jne .LBB16_3
; X86-NEXT: # %bb.1: # %loadbb1
; X86-NEXT: movzbl 4(%eax), %eax
; X86-NEXT: movzbl 4(%ecx), %ecx
; X86-NEXT: subl %ecx, %eax
; X86-NEXT: popl %esi
; X86-NEXT: retl
; X86-NEXT: .LBB16_1: # %res_block
; X86-NEXT: .LBB16_3: # %res_block
; X86-NEXT: setae %al
; X86-NEXT: movzbl %al, %eax
; X86-NEXT: leal -1(%eax,%eax), %eax
; X86-NEXT: popl %esi
; X86-NEXT: retl
;
; X64-LABEL: length5:
; X64: # %bb.0: # %loadbb
; X64: # %bb.0:
; X64-NEXT: movl (%rdi), %eax
; X64-NEXT: movl (%rsi), %ecx
; X64-NEXT: bswapl %eax
; X64-NEXT: bswapl %ecx
; X64-NEXT: cmpl %ecx, %eax
; X64-NEXT: jne .LBB16_1
; X64-NEXT: # %bb.2: # %loadbb1
; X64-NEXT: jne .LBB16_3
; X64-NEXT: # %bb.1: # %loadbb1
; X64-NEXT: movzbl 4(%rdi), %eax
; X64-NEXT: movzbl 4(%rsi), %ecx
; X64-NEXT: subl %ecx, %eax
; X64-NEXT: retq
; X64-NEXT: .LBB16_1: # %res_block
; X64-NEXT: .LBB16_3: # %res_block
; X64-NEXT: setae %al
; X64-NEXT: movzbl %al, %eax
; X64-NEXT: leal -1(%rax,%rax), %eax
Expand Down Expand Up @@ -521,7 +521,7 @@ define i1 @length5_eq(i8* %X, i8* %Y) nounwind {

define i1 @length5_lt(i8* %X, i8* %Y) nounwind {
; X86-LABEL: length5_lt:
; X86: # %bb.0: # %loadbb
; X86: # %bb.0:
; X86-NEXT: pushl %esi
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
Expand All @@ -530,38 +530,38 @@ define i1 @length5_lt(i8* %X, i8* %Y) nounwind {
; X86-NEXT: bswapl %edx
; X86-NEXT: bswapl %esi
; X86-NEXT: cmpl %esi, %edx
; X86-NEXT: jne .LBB18_1
; X86-NEXT: # %bb.2: # %loadbb1
; X86-NEXT: jne .LBB18_3
; X86-NEXT: # %bb.1: # %loadbb1
; X86-NEXT: movzbl 4(%eax), %eax
; X86-NEXT: movzbl 4(%ecx), %ecx
; X86-NEXT: subl %ecx, %eax
; X86-NEXT: jmp .LBB18_3
; X86-NEXT: .LBB18_1: # %res_block
; X86-NEXT: jmp .LBB18_2
; X86-NEXT: .LBB18_3: # %res_block
; X86-NEXT: setae %al
; X86-NEXT: movzbl %al, %eax
; X86-NEXT: leal -1(%eax,%eax), %eax
; X86-NEXT: .LBB18_3: # %endblock
; X86-NEXT: .LBB18_2: # %endblock
; X86-NEXT: shrl $31, %eax
; X86-NEXT: # kill: def $al killed $al killed $eax
; X86-NEXT: popl %esi
; X86-NEXT: retl
;
; X64-LABEL: length5_lt:
; X64: # %bb.0: # %loadbb
; X64: # %bb.0:
; X64-NEXT: movl (%rdi), %eax
; X64-NEXT: movl (%rsi), %ecx
; X64-NEXT: bswapl %eax
; X64-NEXT: bswapl %ecx
; X64-NEXT: cmpl %ecx, %eax
; X64-NEXT: jne .LBB18_1
; X64-NEXT: # %bb.2: # %loadbb1
; X64-NEXT: jne .LBB18_3
; X64-NEXT: # %bb.1: # %loadbb1
; X64-NEXT: movzbl 4(%rdi), %eax
; X64-NEXT: movzbl 4(%rsi), %ecx
; X64-NEXT: subl %ecx, %eax
; X64-NEXT: shrl $31, %eax
; X64-NEXT: # kill: def $al killed $al killed $eax
; X64-NEXT: retq
; X64-NEXT: .LBB18_1: # %res_block
; X64-NEXT: .LBB18_3: # %res_block
; X64-NEXT: setae %al
; X64-NEXT: movzbl %al, %eax
; X64-NEXT: leal -1(%rax,%rax), %eax
Expand Down
40 changes: 20 additions & 20 deletions llvm/test/CodeGen/X86/memcmp-optsize.ll
View file
Expand Up @@ -111,7 +111,7 @@ define i1 @length2_eq_nobuiltin_attr(i8* %X, i8* %Y) nounwind optsize {

define i32 @length3(i8* %X, i8* %Y) nounwind optsize {
; X86-LABEL: length3:
; X86: # %bb.0: # %loadbb
; X86: # %bb.0:
; X86-NEXT: pushl %esi
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
Expand All @@ -120,34 +120,34 @@ define i32 @length3(i8* %X, i8* %Y) nounwind optsize {
; X86-NEXT: rolw $8, %dx
; X86-NEXT: rolw $8, %si
; X86-NEXT: cmpw %si, %dx
; X86-NEXT: jne .LBB4_1
; X86-NEXT: # %bb.2: # %loadbb1
; X86-NEXT: jne .LBB4_3
; X86-NEXT: # %bb.1: # %loadbb1
; X86-NEXT: movzbl 2(%eax), %eax
; X86-NEXT: movzbl 2(%ecx), %ecx
; X86-NEXT: subl %ecx, %eax
; X86-NEXT: jmp .LBB4_3
; X86-NEXT: .LBB4_1: # %res_block
; X86-NEXT: jmp .LBB4_2
; X86-NEXT: .LBB4_3: # %res_block
; X86-NEXT: setae %al
; X86-NEXT: movzbl %al, %eax
; X86-NEXT: leal -1(%eax,%eax), %eax
; X86-NEXT: .LBB4_3: # %endblock
; X86-NEXT: .LBB4_2: # %endblock
; X86-NEXT: popl %esi
; X86-NEXT: retl
;
; X64-LABEL: length3:
; X64: # %bb.0: # %loadbb
; X64: # %bb.0:
; X64-NEXT: movzwl (%rdi), %eax
; X64-NEXT: movzwl (%rsi), %ecx
; X64-NEXT: rolw $8, %ax
; X64-NEXT: rolw $8, %cx
; X64-NEXT: cmpw %cx, %ax
; X64-NEXT: jne .LBB4_1
; X64-NEXT: # %bb.2: # %loadbb1
; X64-NEXT: jne .LBB4_3
; X64-NEXT: # %bb.1: # %loadbb1
; X64-NEXT: movzbl 2(%rdi), %eax
; X64-NEXT: movzbl 2(%rsi), %ecx
; X64-NEXT: subl %ecx, %eax
; X64-NEXT: retq
; X64-NEXT: .LBB4_1: # %res_block
; X64-NEXT: .LBB4_3: # %res_block
; X64-NEXT: setae %al
; X64-NEXT: movzbl %al, %eax
; X64-NEXT: leal -1(%rax,%rax), %eax
Expand Down Expand Up @@ -256,7 +256,7 @@ define i1 @length4_eq_const(i8* %X) nounwind optsize {

define i32 @length5(i8* %X, i8* %Y) nounwind optsize {
; X86-LABEL: length5:
; X86: # %bb.0: # %loadbb
; X86: # %bb.0:
; X86-NEXT: pushl %esi
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
Expand All @@ -265,34 +265,34 @@ define i32 @length5(i8* %X, i8* %Y) nounwind optsize {
; X86-NEXT: bswapl %edx
; X86-NEXT: bswapl %esi
; X86-NEXT: cmpl %esi, %edx
; X86-NEXT: jne .LBB9_1
; X86-NEXT: # %bb.2: # %loadbb1
; X86-NEXT: jne .LBB9_3
; X86-NEXT: # %bb.1: # %loadbb1
; X86-NEXT: movzbl 4(%eax), %eax
; X86-NEXT: movzbl 4(%ecx), %ecx
; X86-NEXT: subl %ecx, %eax
; X86-NEXT: jmp .LBB9_3
; X86-NEXT: .LBB9_1: # %res_block
; X86-NEXT: jmp .LBB9_2
; X86-NEXT: .LBB9_3: # %res_block
; X86-NEXT: setae %al
; X86-NEXT: movzbl %al, %eax
; X86-NEXT: leal -1(%eax,%eax), %eax
; X86-NEXT: .LBB9_3: # %endblock
; X86-NEXT: .LBB9_2: # %endblock
; X86-NEXT: popl %esi
; X86-NEXT: retl
;
; X64-LABEL: length5:
; X64: # %bb.0: # %loadbb
; X64: # %bb.0:
; X64-NEXT: movl (%rdi), %eax
; X64-NEXT: movl (%rsi), %ecx
; X64-NEXT: bswapl %eax
; X64-NEXT: bswapl %ecx
; X64-NEXT: cmpl %ecx, %eax
; X64-NEXT: jne .LBB9_1
; X64-NEXT: # %bb.2: # %loadbb1
; X64-NEXT: jne .LBB9_3
; X64-NEXT: # %bb.1: # %loadbb1
; X64-NEXT: movzbl 4(%rdi), %eax
; X64-NEXT: movzbl 4(%rsi), %ecx
; X64-NEXT: subl %ecx, %eax
; X64-NEXT: retq
; X64-NEXT: .LBB9_1: # %res_block
; X64-NEXT: .LBB9_3: # %res_block
; X64-NEXT: setae %al
; X64-NEXT: movzbl %al, %eax
; X64-NEXT: leal -1(%rax,%rax), %eax
Expand Down

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