3a7578c658
This patch does an inline expansion of memcmp. It changes the memcmp library call into an inline expansion when the size is known at compile time and is under a target specified threshold. This expansion is implemented in CodeGenPrepare and expands into straight line code. The target specifies a maximum load size and the expansion works by using this size to load the two sources, compare, and exit early if a difference is found. It also has a special case when the memcmp result is used in a compare to zero equality. Differential Revision: https://reviews.llvm.org/D28637 llvm-svn: 304313
88 lines
3.0 KiB
LLVM
88 lines
3.0 KiB
LLVM
; RUN: llc -verify-machineinstrs -mcpu=pwr8 -mtriple=powerpc64le-unknown-gnu-linux < %s | FileCheck %s -check-prefix=CHECK
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; Check size 8
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; Function Attrs: nounwind readonly
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define signext i32 @test1(i32* nocapture readonly %buffer1, i32* nocapture readonly %buffer2) local_unnamed_addr #0 {
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entry:
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%0 = bitcast i32* %buffer1 to i8*
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%1 = bitcast i32* %buffer2 to i8*
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%call = tail call signext i32 @memcmp(i8* %0, i8* %1, i64 8) #2
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ret i32 %call
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; CHECK-LABEL: @test1
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; CHECK: ldbrx [[LOAD1:[0-9]+]]
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; CHECK-NEXT: ldbrx [[LOAD2:[0-9]+]]
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; CHECK-NEXT: li [[LI:[0-9]+]], 1
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; CHECK-NEXT: cmpld [[CMPLD:[0-9]+]], [[LOAD1]], [[LOAD2]]
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; CHECK-NEXT: subf. [[SUB:[0-9]+]], [[LOAD2]], [[LOAD1]]
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; CHECK-NEXT: li [[LI2:[0-9]+]], -1
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; CHECK-NEXT: isel [[ISEL:[0-9]+]], [[LI2]], [[LI]], 4
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; CHECK-NEXT: isel [[ISEL2:[0-9]+]], 0, [[ISEL]], 2
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; CHECK-NEXT: extsw 3, [[ISEL2]]
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; CHECK-NEXT: blr
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}
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; Check size 4
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; Function Attrs: nounwind readonly
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define signext i32 @test2(i32* nocapture readonly %buffer1, i32* nocapture readonly %buffer2) local_unnamed_addr #0 {
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entry:
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%0 = bitcast i32* %buffer1 to i8*
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%1 = bitcast i32* %buffer2 to i8*
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%call = tail call signext i32 @memcmp(i8* %0, i8* %1, i64 4) #2
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ret i32 %call
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; CHECK-LABEL: @test2
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; CHECK: lwbrx [[LOAD1:[0-9]+]]
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; CHECK-NEXT: lwbrx [[LOAD2:[0-9]+]]
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; CHECK-NEXT: li [[LI:[0-9]+]], 1
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; CHECK-NEXT: cmpld [[CMPLD:[0-9]+]], [[LOAD1]], [[LOAD2]]
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; CHECK-NEXT: subf. [[SUB:[0-9]+]], [[LOAD2]], [[LOAD1]]
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; CHECK-NEXT: li [[LI2:[0-9]+]], -1
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; CHECK-NEXT: isel [[ISEL:[0-9]+]], [[LI2]], [[LI]], 4
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; CHECK-NEXT: isel [[ISEL2:[0-9]+]], 0, [[ISEL]], 2
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; CHECK-NEXT: extsw 3, [[ISEL2]]
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; CHECK-NEXT: blr
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}
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; Check size 2
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; Function Attrs: nounwind readonly
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define signext i32 @test3(i32* nocapture readonly %buffer1, i32* nocapture readonly %buffer2) local_unnamed_addr #0 {
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entry:
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%0 = bitcast i32* %buffer1 to i8*
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%1 = bitcast i32* %buffer2 to i8*
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%call = tail call signext i32 @memcmp(i8* %0, i8* %1, i64 2) #2
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ret i32 %call
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; CHECK-LABEL: @test3
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; CHECK: lhbrx [[LOAD1:[0-9]+]]
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; CHECK-NEXT: lhbrx [[LOAD2:[0-9]+]]
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; CHECK-NEXT: li [[LI:[0-9]+]], 1
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; CHECK-NEXT: cmpld [[CMPLD:[0-9]+]], [[LOAD1]], [[LOAD2]]
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; CHECK-NEXT: subf. [[SUB:[0-9]+]], [[LOAD2]], [[LOAD1]]
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; CHECK-NEXT: li [[LI2:[0-9]+]], -1
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; CHECK-NEXT: isel [[ISEL:[0-9]+]], [[LI2]], [[LI]], 4
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; CHECK-NEXT: isel [[ISEL2:[0-9]+]], 0, [[ISEL]], 2
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; CHECK-NEXT: extsw 3, [[ISEL2]]
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; CHECK-NEXT: blr
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}
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; Check size 1
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; Function Attrs: nounwind readonly
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define signext i32 @test4(i32* nocapture readonly %buffer1, i32* nocapture readonly %buffer2) local_unnamed_addr #0 {
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entry:
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%0 = bitcast i32* %buffer1 to i8*
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%1 = bitcast i32* %buffer2 to i8*
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%call = tail call signext i32 @memcmp(i8* %0, i8* %1, i64 1) #2
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ret i32 %call
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; CHECK-LABEL: @test4
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; CHECK: lbz [[LOAD1:[0-9]+]]
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; CHECK-NEXT: lbz [[LOAD2:[0-9]+]]
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; CHECK-NEXT: subf [[SUB:[0-9]+]], [[LOAD2]], [[LOAD1]]
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; CHECK-NEXT: extsw 3, [[SUB]]
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; CHECK-NEXT: blr
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}
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; Function Attrs: nounwind readonly
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declare signext i32 @memcmp(i8*, i8*, i64) #1
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