llvm-6502/test/Transforms/Mem2Reg/2005-06-30-ReadBeforeWrite.ll

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; RUN: opt < %s -mem2reg -instcombine -S | grep store
; PR590
define void @zero(i8* %p, i32 %n) {
entry:
%p_addr = alloca i8* ; <i8**> [#uses=2]
%n_addr = alloca i32 ; <i32*> [#uses=2]
%i = alloca i32 ; <i32*> [#uses=6]
%out = alloca i32 ; <i32*> [#uses=2]
%undef = alloca i32 ; <i32*> [#uses=2]
store i8* %p, i8** %p_addr
store i32 %n, i32* %n_addr
store i32 0, i32* %i
br label %loopentry
loopentry: ; preds = %endif, %entry
%tmp.0 = load i32* %n_addr ; <i32> [#uses=1]
%tmp.1 = add i32 %tmp.0, 1 ; <i32> [#uses=1]
%tmp.2 = load i32* %i ; <i32> [#uses=1]
%tmp.3 = icmp sgt i32 %tmp.1, %tmp.2 ; <i1> [#uses=2]
%tmp.4 = zext i1 %tmp.3 to i32 ; <i32> [#uses=0]
br i1 %tmp.3, label %no_exit, label %return
no_exit: ; preds = %loopentry
%tmp.5 = load i32* %undef ; <i32> [#uses=1]
store i32 %tmp.5, i32* %out
store i32 0, i32* %undef
%tmp.6 = load i32* %i ; <i32> [#uses=1]
%tmp.7 = icmp sgt i32 %tmp.6, 0 ; <i1> [#uses=2]
%tmp.8 = zext i1 %tmp.7 to i32 ; <i32> [#uses=0]
br i1 %tmp.7, label %then, label %endif
then: ; preds = %no_exit
%tmp.9 = load i8** %p_addr ; <i8*> [#uses=1]
%tmp.10 = load i32* %i ; <i32> [#uses=1]
%tmp.11 = sub i32 %tmp.10, 1 ; <i32> [#uses=1]
%tmp.12 = getelementptr i8* %tmp.9, i32 %tmp.11 ; <i8*> [#uses=1]
%tmp.13 = load i32* %out ; <i32> [#uses=1]
%tmp.14 = trunc i32 %tmp.13 to i8 ; <i8> [#uses=1]
store i8 %tmp.14, i8* %tmp.12
br label %endif
endif: ; preds = %then, %no_exit
%tmp.15 = load i32* %i ; <i32> [#uses=1]
%inc = add i32 %tmp.15, 1 ; <i32> [#uses=1]
store i32 %inc, i32* %i
br label %loopentry
return: ; preds = %loopentry
ret void
}