diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Target/README.txt | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/llvm/lib/Target/README.txt b/llvm/lib/Target/README.txt index a345d3ddb41..7018b61f68f 100644 --- a/llvm/lib/Target/README.txt +++ b/llvm/lib/Target/README.txt @@ -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 |
