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[MetaRenamer] Don't rename library functions.

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Library functions can have specific semantics that affect the behavior of
certain passes. DSE, for instance, gives special treatment to malloc-ed pointers
but not to pointers returned from an equivalently typed (but differently named)
function.

MetaRenamer ought not to alter program semantics, so library functions must
remain untouched.

Reviewers: mehdi_amini, majnemer, chandlerc, davide

Reviewed By: davide

Subscribers: davide, llvm-commits

Differential Revision: https://reviews.llvm.org/D31304

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298659 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bryant Wong 2017-03-23 23:21:07 +00:00
parent 261eb1f850
commit 69af69a8ff
2 changed files with 29 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
lib/Transforms/Utils/MetaRenamer.cpp
View File

@ -16,6 +16,7 @@
#include "llvm/Transforms/IPO.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Module.h"
@ -67,6 +68,7 @@ namespace {
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.setPreservesAll();
}
@ -110,9 +112,15 @@ namespace {
}
// Rename all functions
const TargetLibraryInfo &TLI =
getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
for (auto &F : M) {
StringRef Name = F.getName();
if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
LibFunc Tmp;
// Leave library functions alone because their presence or absence could
// affect the behavior of other passes.
if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1) ||
TLI.getLibFunc(F, Tmp))
continue;
F.setName(renamer.newName());
@ -139,8 +147,11 @@ namespace {
}
char MetaRenamer::ID = 0;
INITIALIZE_PASS(MetaRenamer, "metarenamer",
"Assign new names to everything", false, false)
INITIALIZE_PASS_BEGIN(MetaRenamer, "metarenamer",
"Assign new names to everything", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(MetaRenamer, "metarenamer",
"Assign new names to everything", false, false)
//===----------------------------------------------------------------------===//
//
// MetaRenamer - Rename everything with metasyntactic names.

15
test/Transforms/MetaRenamer/metarenamer.ll
View File

@ -96,3 +96,18 @@ define i32 @varargs_func_6_xxx(i32 %arg_1_xxx, i32 %arg_2_xxx, ...) nounwind uwt
store i32 %arg_2_xxx, i32* %2, align 4
ret i32 6
}
declare noalias i8* @malloc(i32)
declare void @free(i8* nocapture)
define void @dont_rename_lib_funcs() {
; CHECK-LABEL: @foo(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[TMP:%.*]] = call i8* @malloc(i32 23)
; CHECK-NEXT: call void @free(i8* [[TMP]])
; CHECK-NEXT: ret void
;
%x = call i8* @malloc(i32 23)
call void @free(i8* %x)
ret void
}