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	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
		
			
				
	
	
		
			41 lines
		
	
	
		
			926 B
		
	
	
	
		
			LLVM
		
	
	
	
	
	
			
		
		
	
	
			41 lines
		
	
	
		
			926 B
		
	
	
	
		
			LLVM
		
	
	
	
	
	
| ; RUN: llvm-as <%s >%t1
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| ; RUN: llvm-lto -exported-symbol=_uses_puts -exported-symbol=_uses_printf -o - %t1 | \
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| ; RUN: llvm-nm | \
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| ; RUN: FileCheck %s
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| ; rdar://problem/16165191
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| ; runtime library implementations should not be renamed
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| 
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| target triple = "x86_64-apple-darwin11"
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| 
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| @str = private unnamed_addr constant [13 x i8] c"hello world\0A\00"
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| 
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| ; CHECK-NOT: U _puts
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| ; CHECK: T _uses_printf
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| ; CHECK: T _uses_puts
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| define i32 @uses_puts(i32 %i) {
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| entry:
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|   %s = call i8* @foo(i32 %i)
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|   %ret = call i32 @puts(i8* %s)
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|   ret i32 %ret
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| }
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| define i32 @uses_printf(i32 %i) {
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| entry:
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|   %s = getelementptr [13 x i8]* @str, i64 0, i64 0
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|   call i32 (i8*, ...)* @printf(i8* %s)
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|   ret i32 0
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| }
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| 
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| define hidden i32 @printf(i8* readonly nocapture %fmt, ...) {
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| entry:
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|   %ret = call i32 @bar(i8* %fmt)
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|   ret i32 %ret
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| }
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| define hidden i32 @puts(i8* %s) {
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| entry:
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|   %ret = call i32 @bar(i8* %s)
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|   ret i32 %ret
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| }
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| 
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| declare i8* @foo(i32)
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| declare i32 @bar(i8*)
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