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	and allow some optimizations to turn conditional branches into unconditional. This commit adds a simple control-flow optimization which merges two consecutive basic blocks which are connected by a single edge. This allows the codegen to operate on larger basic blocks. rdar://11973998 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161852 91177308-0d34-0410-b5e6-96231b3b80d8
		
			
				
	
	
		
			31 lines
		
	
	
		
			929 B
		
	
	
	
		
			LLVM
		
	
	
	
	
	
			
		
		
	
	
			31 lines
		
	
	
		
			929 B
		
	
	
	
		
			LLVM
		
	
	
	
	
	
; RUN: opt -codegenprepare %s -S -o - | FileCheck %s
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
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target triple = "x86_64-apple-darwin10.0.0"
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; CHECK: @test1
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; objectsize should fold to a constant, which causes the branch to fold to an
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; uncond branch. Next, we fold the control flow alltogether.
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; rdar://8785296
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define i32 @test1(i8* %ptr) nounwind ssp noredzone align 2 {
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entry:
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  %0 = tail call i64 @llvm.objectsize.i64(i8* %ptr, i1 false)
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  %1 = icmp ugt i64 %0, 3
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  br i1 %1, label %T, label %trap
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; CHECK: T:
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; CHECK-NOT: br label %
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trap:                                             ; preds = %0, %entry
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  tail call void @llvm.trap() noreturn nounwind
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  unreachable
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T:
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; CHECK: ret i32 4
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  ret i32 4
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}
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declare i64 @llvm.objectsize.i64(i8*, i1) nounwind readonly
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declare void @llvm.trap() nounwind
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