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Optimize conditional branch on i1 phis with non-constant inputs.

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This turns:

eq:
        %3 = icmp eq i32 %1, %2
        br label %join

ne:
        %4 = icmp ne i32 %1, %2
        br label %join

join:
        %5 = phi i1 [%3, %eq], [%4, %ne]
        br i1 %5, label %yes, label %no

=>

eq:
        %3 = icmp eq i32 %1, %2
        br i1 %3, label %yes, label %no

ne:
        %4 = icmp ne i32 %1, %2
        br i1 %4, label %yes, label %no


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69102 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2009-04-14 23:40:03 +00:00
parent 5b9c31841f
commit df2f1189a3
2 changed files with 80 additions and 13 deletions
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26
test/Transforms/CondProp/phisimplify3.ll Normal file
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@@ -0,0 +1,26 @@
; RUN: llvm-as < %s | opt -condprop | llvm-dis | not grep phi
define i32 @foo(i1, i32, i32) {
prologue:
br i1 %0, label %eq, label %ne
eq: ; preds = %prologue
store i32 0, i32* inttoptr (i32 10000 to i32*)
%3 = icmp eq i32 %1, %2 ; <i1> [#uses=1]
br label %join
ne: ; preds = %prologue
%4 = icmp ne i32 %1, %2 ; <i1> [#uses=1]
br label %join
join: ; preds = %ne, %eq
%5 = phi i1 [ %3, %eq ], [ %4, %ne ] ; <i1> [#uses=1]
br i1 %5, label %yes, label %no
yes: ; preds = %join
store i32 0, i32* inttoptr (i32 20000 to i32*)
ret i32 5
no: ; preds = %join
ret i32 20
}