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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86146 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2009-11-05 18:19:19 +00:00
parent 0ff290615f
commit 6c9fab7404
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34
lib/Target/README.txt
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@ -1229,6 +1229,40 @@ GCC PR33344 is a similar case.
//===---------------------------------------------------------------------===//
[PHI TRANSLATE INDEXED GEPs] PR5313
Load redundancy elimination for simple loop. This loop:
void append_text(const char* text,unsigned char * const io) {
while(*text)
*io=*text++;
}
Compiles to have a fully redundant load in the loop (%2):
define void @append_text(i8* nocapture %text, i8* nocapture %io) nounwind {
entry:
%0 = load i8* %text, align 1 ; <i8> [#uses=1]
%1 = icmp eq i8 %0, 0 ; <i1> [#uses=1]
br i1 %1, label %return, label %bb
bb: ; preds = %bb, %entry
%indvar = phi i32 [ 0, %entry ], [ %tmp, %bb ] ; <i32> [#uses=2]
%text_addr.04 = getelementptr i8* %text, i32 %indvar ; <i8*> [#uses=1]
%2 = load i8* %text_addr.04, align 1 ; <i8> [#uses=1]
store i8 %2, i8* %io, align 1
%tmp = add i32 %indvar, 1 ; <i32> [#uses=2]
%scevgep = getelementptr i8* %text, i32 %tmp ; <i8*> [#uses=1]
%3 = load i8* %scevgep, align 1 ; <i8> [#uses=1]
%4 = icmp eq i8 %3, 0 ; <i1> [#uses=1]
br i1 %4, label %return, label %bb
return: ; preds = %bb, %entry
ret void
}
//===---------------------------------------------------------------------===//
There are many load PRE testcases in testsuite/gcc.dg/tree-ssa/loadpre* in the
GCC testsuite. There are many pre testcases as ssa-pre-*.c