llvm-6502/test/LTO/keep-used-puts-during-instcombine.ll
Duncan P. N. Exon Smith f5d17528ee Module: Don't rename in getOrInsertFunction()
During LTO, user-supplied definitions of C library functions often
exist.  -instcombine uses Module::getOrInsertFunction() to get a handle
on library functions (e.g., @puts, when optimizing @printf).

Previously, Module::getOrInsertFunction() would rename any matching
functions with local linkage, and create a new declaration.  In LTO,
this is the opposite of desired behaviour, as it skips by the
user-supplied version of the library function and creates a new
undefined reference which the linker often cannot resolve.

After some discussing with Rafael on the list, it looks like it's
undesired behaviour.  If a consumer actually *needs* this behaviour, we
should add new API with a more explicit name.

I added two testcases: one specifically for the -instcombine behaviour
and one for the LTO flow.

<rdar://problem/16165191>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203513 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-10 23:42:28 +00:00

37 lines
899 B
LLVM

; RUN: opt -S -instcombine <%s | FileCheck %s
; rdar://problem/16165191
; llvm.compiler.used functions should not be renamed
target triple = "x86_64-apple-darwin11"
@llvm.compiler.used = appending global [1 x i8*] [
i8* bitcast (i32(i8*)* @puts to i8*)
], section "llvm.metadata"
@llvm.used = appending global [1 x i8*] [
i8* bitcast (i32(i32)* @uses_printf to i8*)
], section "llvm.metadata"
@str = private unnamed_addr constant [13 x i8] c"hello world\0A\00"
define i32 @uses_printf(i32 %i) {
entry:
%s = getelementptr [13 x i8]* @str, i64 0, i64 0
call i32 (i8*, ...)* @printf(i8* %s)
ret i32 0
}
define internal hidden i32 @printf(i8* readonly nocapture %fmt, ...) {
entry:
%ret = call i32 @bar(i8* %fmt)
ret i32 %ret
}
; CHECK: define {{.*}} @puts(
define internal hidden i32 @puts(i8* %s) {
entry:
%ret = call i32 @bar(i8* %s)
ret i32 %ret
}
declare i32 @bar(i8*)