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	present in the bottom of the CFG triangle, as the transformation isn't ever valuable if the branch can't be eliminated. Also, unify some heuristics between SimplifyCFG's multiple if-converters, for consistency. This fixes rdar://10627242. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147630 91177308-0d34-0410-b5e6-96231b3b80d8
		
			
				
	
	
		
			139 lines
		
	
	
		
			3.2 KiB
		
	
	
	
		
			LLVM
		
	
	
	
	
	
			
		
		
	
	
			139 lines
		
	
	
		
			3.2 KiB
		
	
	
	
		
			LLVM
		
	
	
	
	
	
; RUN: opt < %s -simplifycfg -S | FileCheck %s
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; Test basic folding to a conditional branch.
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define i32 @foo(i64 %x, i64 %y) nounwind {
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; CHECK: @foo
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entry:
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    %eq = icmp eq i64 %x, %y
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    br i1 %eq, label %b, label %switch
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switch:
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    %lt = icmp slt i64 %x, %y
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; CHECK: br i1 %lt, label %a, label %b
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    %qux = select i1 %lt, i32 0, i32 2
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    switch i32 %qux, label %bees [
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        i32 0, label %a
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        i32 1, label %b
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        i32 2, label %b
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    ]
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a:
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    tail call void @bees.a() nounwind
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    ret i32 1
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; CHECK: b:
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; CHECK-NEXT: %retval = phi i32 [ 0, %switch ], [ 2, %entry ]
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b:
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    %retval = phi i32 [0, %switch], [0, %switch], [2, %entry]
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    tail call void @bees.b() nounwind
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    ret i32 %retval
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; CHECK-NOT: bees:
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bees:
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    tail call void @llvm.trap() nounwind
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    unreachable
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}
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; Test basic folding to an unconditional branch.
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define i32 @bar(i64 %x, i64 %y) nounwind {
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; CHECK: @bar
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entry:
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; CHECK-NEXT: entry:
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; CHECK-NEXT: tail call void @bees.a() nounwind
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; CHECK-NEXT: ret i32 0
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    %lt = icmp slt i64 %x, %y
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    %qux = select i1 %lt, i32 0, i32 2
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    switch i32 %qux, label %bees [
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        i32 0, label %a
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        i32 1, label %b
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        i32 2, label %a
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    ]
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a:
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    %retval = phi i32 [0, %entry], [0, %entry], [1, %b]
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    tail call void @bees.a() nounwind
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    ret i32 0
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b:
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    tail call void @bees.b() nounwind
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    br label %a
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bees:
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    tail call void @llvm.trap() nounwind
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    unreachable
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}
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; Test the edge case where both values from the select are the default case.
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define void @bazz(i64 %x, i64 %y) nounwind {
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; CHECK: @bazz
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entry:
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; CHECK-NEXT: entry:
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; CHECK-NEXT: tail call void @bees.b() nounwind
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; CHECK-NEXT: ret void
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    %lt = icmp slt i64 %x, %y
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    %qux = select i1 %lt, i32 10, i32 12
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    switch i32 %qux, label %b [
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        i32 0, label %a
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        i32 1, label %bees
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        i32 2, label %bees
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    ]
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a:
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    tail call void @bees.a() nounwind
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    ret void
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b:
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    tail call void @bees.b() nounwind
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    ret void
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bees:
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    tail call void @llvm.trap()
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    unreachable
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}
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; Test the edge case where both values from the select are equal.
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define void @quux(i64 %x, i64 %y) nounwind {
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; CHECK: @quux
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entry:
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; CHECK-NEXT: entry:
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; CHECK-NEXT: tail call void @bees.a() nounwind
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; CHECK-NEXT: ret void
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    %lt = icmp slt i64 %x, %y
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    %qux = select i1 %lt, i32 0, i32 0
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    switch i32 %qux, label %b [
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        i32 0, label %a
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        i32 1, label %bees
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        i32 2, label %bees
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    ]
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a:
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    tail call void @bees.a() nounwind
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    ret void
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b:
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    tail call void @bees.b() nounwind
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    ret void
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bees:
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    tail call void @llvm.trap()
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    unreachable
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}
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; A final test, for phi node munging.
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define i32 @xyzzy(i64 %x, i64 %y) {
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; CHECK: @xyzzy
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entry:
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    %eq = icmp eq i64 %x, %y
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    br i1 %eq, label %r, label %cont
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cont:
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; CHECK: %lt = icmp slt i64 %x, %y
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    %lt = icmp slt i64 %x, %y
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; CHECK-NEXT: select i1 %lt, i32 -1, i32 1
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    %qux = select i1 %lt, i32 0, i32 2
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    switch i32 %qux, label %bees [
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        i32 0, label %a
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        i32 1, label %r
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        i32 2, label %r
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    ]
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r:
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    %val = phi i32 [0, %entry], [1, %cont], [1, %cont]
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    ret i32 %val
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a:
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    ret i32 -1
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; CHECK-NOT: bees:
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bees:
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    tail call void @llvm.trap()
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    unreachable
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}
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declare void @llvm.trap() nounwind noreturn
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declare void @bees.a() nounwind
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declare void @bees.b() nounwind
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