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	local frame causes problem.
For example:
void f(StructToPass s) {
  g(&s, sizeof(s));
}
will cause problem with tail-call since part of s is passed via registers and
saved in f's local frame. When g tries to access s, part of s may be corrupted
since f's local frame is popped out before the tail-call.
The current fix is to disable tail-call if getVarArgsRegSaveSize is not 0 for
the caller. This is a conservative approach, if we can prove the address of
s or part of s is not taken and passed to g, it should be okay to perform
tail-call.
rdar://12442472
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165853 91177308-0d34-0410-b5e6-96231b3b80d8
		
	
		
			
				
	
	
		
			91 lines
		
	
	
		
			2.5 KiB
		
	
	
	
		
			LLVM
		
	
	
	
	
	
			
		
		
	
	
			91 lines
		
	
	
		
			2.5 KiB
		
	
	
	
		
			LLVM
		
	
	
	
	
	
; RUN: llc < %s -mtriple=armv7-apple-ios6.0 | FileCheck %s
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; rdar://9877866
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%struct.SmallStruct = type { i32, [8 x i32], [37 x i8] }
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%struct.LargeStruct = type { i32, [1001 x i8], [300 x i32] }
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define i32 @f() nounwind ssp {
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entry:
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; CHECK: f:
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; CHECK: ldr
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; CHECK: str
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; CHECK-NOT:bne
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  %st = alloca %struct.SmallStruct, align 4
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  %call = call i32 @e1(%struct.SmallStruct* byval %st)
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  ret i32 0
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}
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; Generate a loop for large struct byval
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define i32 @g() nounwind ssp {
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entry:
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; CHECK: g:
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; CHECK: ldr
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; CHECK: sub
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; CHECK: str
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; CHECK: bne
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  %st = alloca %struct.LargeStruct, align 4
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  %call = call i32 @e2(%struct.LargeStruct* byval %st)
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  ret i32 0
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}
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; Generate a loop using NEON instructions
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define i32 @h() nounwind ssp {
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entry:
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; CHECK: h:
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; CHECK: vld1
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; CHECK: sub
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; CHECK: vst1
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; CHECK: bne
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  %st = alloca %struct.LargeStruct, align 16
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  %call = call i32 @e3(%struct.LargeStruct* byval align 16 %st)
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  ret i32 0
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}
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declare i32 @e1(%struct.SmallStruct* nocapture byval %in) nounwind
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declare i32 @e2(%struct.LargeStruct* nocapture byval %in) nounwind
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declare i32 @e3(%struct.LargeStruct* nocapture byval align 16 %in) nounwind
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; rdar://12442472
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; We can't do tail call since address of s is passed to the callee and part of
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; s is in caller's local frame.
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define void @f3(%struct.SmallStruct* nocapture byval %s) nounwind optsize {
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; CHECK: f3
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; CHECK: bl _consumestruct
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entry:
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  %0 = bitcast %struct.SmallStruct* %s to i8*
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  tail call void @consumestruct(i8* %0, i32 80) optsize
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  ret void
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}
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define void @f4(%struct.SmallStruct* nocapture byval %s) nounwind optsize {
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; CHECK: f4
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; CHECK: bl _consumestruct
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entry:
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  %addr = getelementptr inbounds %struct.SmallStruct* %s, i32 0, i32 0
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  %0 = bitcast i32* %addr to i8*
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  tail call void @consumestruct(i8* %0, i32 80) optsize
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  ret void
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}
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; We can do tail call here since s is in the incoming argument area.
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define void @f5(i32 %a, i32 %b, i32 %c, i32 %d, %struct.SmallStruct* nocapture byval %s) nounwind optsize {
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; CHECK: f5
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; CHECK: b _consumestruct
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entry:
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  %0 = bitcast %struct.SmallStruct* %s to i8*
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  tail call void @consumestruct(i8* %0, i32 80) optsize
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  ret void
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}
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define void @f6(i32 %a, i32 %b, i32 %c, i32 %d, %struct.SmallStruct* nocapture byval %s) nounwind optsize {
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; CHECK: f6
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; CHECK: b _consumestruct
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entry:
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  %addr = getelementptr inbounds %struct.SmallStruct* %s, i32 0, i32 0
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  %0 = bitcast i32* %addr to i8*
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  tail call void @consumestruct(i8* %0, i32 80) optsize
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  ret void
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}
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declare void @consumestruct(i8* nocapture %structp, i32 %structsize) nounwind
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