llvm/test/CodeGen/X86/memcmp.ll
Jim Grosbach e1af5f6ad1 X86: Perform integer comparisons at i32 or larger.
Utilizing the 8 and 16 bit comparison instructions, even when an input can
be folded into the comparison instruction itself, is typically not worth it.
There are too many partial register stalls as a result, leading to significant
slowdowns. By always performing comparisons on at least 32-bit
registers, performance of the calculation chain leading to the
comparison improves. Continue to use the smaller comparisons when
minimizing size, as that allows better folding of loads into the
comparison instructions.

rdar://15386341

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195496 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-22 19:57:47 +00:00

117 lines
3.6 KiB
LLVM

; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s
; RUN: llc < %s -disable-simplify-libcalls -mtriple=x86_64-linux | FileCheck %s --check-prefix=NOBUILTIN
; RUN: llc < %s -mtriple=x86_64-win32 | FileCheck %s
; This tests codegen time inlining/optimization of memcmp
; rdar://6480398
@.str = private constant [23 x i8] c"fooooooooooooooooooooo\00", align 1 ; <[23 x i8]*> [#uses=1]
declare i32 @memcmp(...)
define void @memcmp2(i8* %X, i8* %Y, i32* nocapture %P) nounwind {
entry:
%0 = tail call i32 (...)* @memcmp(i8* %X, i8* %Y, i32 2) nounwind ; <i32> [#uses=1]
%1 = icmp eq i32 %0, 0 ; <i1> [#uses=1]
br i1 %1, label %return, label %bb
bb: ; preds = %entry
store i32 4, i32* %P, align 4
ret void
return: ; preds = %entry
ret void
; CHECK-LABEL: memcmp2:
; CHECK: movzwl
; CHECK-NEXT: movzwl
; CHECK-NEXT: cmpl
; NOBUILTIN-LABEL: memcmp2:
; NOBUILTIN: callq
}
define void @memcmp2a(i8* %X, i32* nocapture %P) nounwind {
entry:
%0 = tail call i32 (...)* @memcmp(i8* %X, i8* getelementptr inbounds ([23 x i8]* @.str, i32 0, i32 1), i32 2) nounwind ; <i32> [#uses=1]
%1 = icmp eq i32 %0, 0 ; <i1> [#uses=1]
br i1 %1, label %return, label %bb
bb: ; preds = %entry
store i32 4, i32* %P, align 4
ret void
return: ; preds = %entry
ret void
; CHECK-LABEL: memcmp2a:
; CHECK: movzwl
; CHECK-NEXT: cmpl $28527,
}
define void @memcmp4(i8* %X, i8* %Y, i32* nocapture %P) nounwind {
entry:
%0 = tail call i32 (...)* @memcmp(i8* %X, i8* %Y, i32 4) nounwind ; <i32> [#uses=1]
%1 = icmp eq i32 %0, 0 ; <i1> [#uses=1]
br i1 %1, label %return, label %bb
bb: ; preds = %entry
store i32 4, i32* %P, align 4
ret void
return: ; preds = %entry
ret void
; CHECK-LABEL: memcmp4:
; CHECK: movl
; CHECK-NEXT: cmpl
}
define void @memcmp4a(i8* %X, i32* nocapture %P) nounwind {
entry:
%0 = tail call i32 (...)* @memcmp(i8* %X, i8* getelementptr inbounds ([23 x i8]* @.str, i32 0, i32 1), i32 4) nounwind ; <i32> [#uses=1]
%1 = icmp eq i32 %0, 0 ; <i1> [#uses=1]
br i1 %1, label %return, label %bb
bb: ; preds = %entry
store i32 4, i32* %P, align 4
ret void
return: ; preds = %entry
ret void
; CHECK-LABEL: memcmp4a:
; CHECK: cmpl $1869573999,
}
define void @memcmp8(i8* %X, i8* %Y, i32* nocapture %P) nounwind {
entry:
%0 = tail call i32 (...)* @memcmp(i8* %X, i8* %Y, i32 8) nounwind ; <i32> [#uses=1]
%1 = icmp eq i32 %0, 0 ; <i1> [#uses=1]
br i1 %1, label %return, label %bb
bb: ; preds = %entry
store i32 4, i32* %P, align 4
ret void
return: ; preds = %entry
ret void
; CHECK-LABEL: memcmp8:
; CHECK: movq
; CHECK: cmpq
}
define void @memcmp8a(i8* %X, i32* nocapture %P) nounwind {
entry:
%0 = tail call i32 (...)* @memcmp(i8* %X, i8* getelementptr inbounds ([23 x i8]* @.str, i32 0, i32 0), i32 8) nounwind ; <i32> [#uses=1]
%1 = icmp eq i32 %0, 0 ; <i1> [#uses=1]
br i1 %1, label %return, label %bb
bb: ; preds = %entry
store i32 4, i32* %P, align 4
ret void
return: ; preds = %entry
ret void
; CHECK-LABEL: memcmp8a:
; CHECK: movabsq $8029759185026510694,
; CHECK: cmpq
}