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[CGP] don't expand a memcmp with nobuiltin attribute

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This matches the behavior used in the SDAG when expanding memcmp.

For reference, we're intentionally treating the earlier fortified call transforms differently after:
https://bugs.llvm.org/show_bug.cgi?id=23093
https://reviews.llvm.org/rL233776

One motivation for not transforming nobuiltin calls is that it can interfere with sanitizers:
https://reviews.llvm.org/D19781
https://reviews.llvm.org/D19801

Differential Revision: https://reviews.llvm.org/D34043


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305007 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjay Patel 2017-06-08 19:47:25 +00:00
parent b45962cb21
commit 4c04c2d072
3 changed files with 27 additions and 12 deletions
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8
include/llvm/Analysis/TargetLibraryInfo.h
View File

@ -13,6 +13,7 @@
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/Triple.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
@ -239,6 +240,13 @@ public:
return Impl->getLibFunc(FDecl, F);
}
/// If a callsite does not have the 'nobuiltin' attribute, return if the
/// called function is a known library function and set F to that function.
bool getLibFunc(ImmutableCallSite CS, LibFunc & F) const {
return !CS.isNoBuiltin() && CS.getCalledFunction() &&
getLibFunc(*(CS.getCalledFunction()), F);
}
/// Tests whether a library function is available.
bool has(LibFunc F) const {
return Impl->getState(F) != TargetLibraryInfoImpl::Unavailable;

10
lib/CodeGen/CodeGenPrepare.cpp
View File

@ -2406,12 +2406,10 @@ bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool& ModifiedDT) {
}
LibFunc Func;
if (TLInfo->getLibFunc(*CI->getCalledFunction(), Func) &&
Func == LibFunc_memcmp) {
if (expandMemCmp(CI, TTI, TLI, DL)) {
ModifiedDT = true;
return true;
}
if (TLInfo->getLibFunc(ImmutableCallSite(CI), Func) &&
Func == LibFunc_memcmp && expandMemCmp(CI, TTI, TLI, DL)) {
ModifiedDT = true;
return true;
}
return false;
}

21
test/CodeGen/PowerPC/memCmpUsedInZeroEqualityComparison.ll
View File

@ -199,12 +199,21 @@ define signext i32 @zeroEqualityTest06() {
define i1 @length2_eq_nobuiltin_attr(i8* %X, i8* %Y) {
; CHECK-LABEL: length2_eq_nobuiltin_attr:
; CHECK: # BB#0:
; CHECK-NEXT: lhz 3, 0(3)
; CHECK-NEXT: lhz 4, 0(4)
; CHECK-NEXT: li 5, 0
; CHECK-NEXT: li 12, 1
; CHECK-NEXT: cmpw 3, 4
; CHECK-NEXT: isel 3, 12, 5, 2
; CHECK-NEXT: mflr 0
; CHECK-NEXT: std 0, 16(1)
; CHECK-NEXT: stdu 1, -32(1)
; CHECK-NEXT: .Lcfi0:
; CHECK-NEXT: .cfi_def_cfa_offset 32
; CHECK-NEXT: .Lcfi1:
; CHECK-NEXT: .cfi_offset lr, 16
; CHECK-NEXT: li 5, 2
; CHECK-NEXT: bl memcmp
; CHECK-NEXT: nop
; CHECK-NEXT: cntlzw 3, 3
; CHECK-NEXT: rlwinm 3, 3, 27, 31, 31
; CHECK-NEXT: addi 1, 1, 32
; CHECK-NEXT: ld 0, 16(1)
; CHECK-NEXT: mtlr 0
; CHECK-NEXT: blr
%m = tail call signext i32 @memcmp(i8* %X, i8* %Y, i64 2) nobuiltin
%c = icmp eq i32 %m, 0