81f3fd4bf8
If bottom of block BB has only one successor OldTop, in most cases it is profitable to move it before OldTop, except the following case:
-->OldTop<-
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---Pred |
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BB-----
Move BB before OldTop can't reduce the number of taken branches, this patch detects this case and prevent the moving.
Differential Revision: https://reviews.llvm.org/D57067
llvm-svn: 352236
37 lines
767 B
LLVM
37 lines
767 B
LLVM
; RUN: llc -mtriple=i686-linux < %s | FileCheck %s
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define i32 @bar(i32 %count) {
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; Test checks that basic block backedge2 is not moved before header,
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; because it can't reduce taken branches.
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; Later backedge1 and backedge2 is rotated before loop header.
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; CHECK-LABEL: bar
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; CHECK: %.entry
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; CHECK: %.backedge1
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; CHECK: %.backedge2
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; CHECK: %.header
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; CHECK: %.exit
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.entry:
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%c = shl nsw i32 %count, 2
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br label %.header
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.header:
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%val1 = call i32 @foo()
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%cond1 = icmp sgt i32 %val1, 1
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br i1 %cond1, label %.exit, label %.backedge1
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.backedge1:
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%val2 = call i32 @foo()
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%cond2 = icmp sgt i32 %val2, 1
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br i1 %cond2, label %.header, label %.backedge2
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.backedge2:
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%val3 = call i32 @foo()
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br label %.header
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.exit:
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ret i32 %c
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}
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declare i32 @foo()
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