new testcase for PR590

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22317 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/Mem2Reg/2005-06-30-ReadBeforeWrite.ll b/test/Transforms/Mem2Reg/2005-06-30-ReadBeforeWrite.ll
new file mode 100644 (file)
index 0000000..a6d4696
--- /dev/null
+++ b/test/Transforms/Mem2Reg/2005-06-30-ReadBeforeWrite.ll
@@ -0,0 +1,51 @@
+; RUN: llvm-as < %s | opt -mem2reg -instcombine | llvm-dis | grep store
+; PR590
+
+void %zero(sbyte* %p, int %n) {
+entry:
+       %p_addr = alloca sbyte*         ; <sbyte**> [#uses=2]
+       %n_addr = alloca int            ; <int*> [#uses=2]
+       %i = alloca int         ; <int*> [#uses=6]
+       %out = alloca int               ; <int*> [#uses=2]
+       %undef = alloca int             ; <int*> [#uses=2]
+       store sbyte* %p, sbyte** %p_addr
+       store int %n, int* %n_addr
+       store int 0, int* %i
+       br label %loopentry
+
+loopentry:             ; preds = %endif, %entry
+       %tmp.0 = load int* %n_addr              ; <int> [#uses=1]
+       %tmp.1 = add int %tmp.0, 1              ; <int> [#uses=1]
+       %tmp.2 = load int* %i           ; <int> [#uses=1]
+       %tmp.3 = setgt int %tmp.1, %tmp.2               ; <bool> [#uses=2]
+       %tmp.4 = cast bool %tmp.3 to int                ; <int> [#uses=0]
+       br bool %tmp.3, label %no_exit, label %return
+
+no_exit:               ; preds = %loopentry
+       %tmp.5 = load int* %undef               ; <int> [#uses=1]
+       store int %tmp.5, int* %out
+       store int 0, int* %undef
+       %tmp.6 = load int* %i           ; <int> [#uses=1]
+       %tmp.7 = setgt int %tmp.6, 0            ; <bool> [#uses=2]
+       %tmp.8 = cast bool %tmp.7 to int                ; <int> [#uses=0]
+       br bool %tmp.7, label %then, label %endif
+
+then:          ; preds = %no_exit
+       %tmp.9 = load sbyte** %p_addr           ; <sbyte*> [#uses=1]
+       %tmp.10 = load int* %i          ; <int> [#uses=1]
+       %tmp.11 = sub int %tmp.10, 1            ; <int> [#uses=1]
+       %tmp.12 = getelementptr sbyte* %tmp.9, int %tmp.11              ; <sbyte*> [#uses=1]
+       %tmp.13 = load int* %out                ; <int> [#uses=1]
+       %tmp.14 = cast int %tmp.13 to sbyte             ; <sbyte> [#uses=1]
+       store sbyte %tmp.14, sbyte* %tmp.12
+       br label %endif
+
+endif:         ; preds = %then, %no_exit
+       %tmp.15 = load int* %i          ; <int> [#uses=1]
+       %inc = add int %tmp.15, 1               ; <int> [#uses=1]
+       store int %inc, int* %i
+       br label %loopentry
+
+return:                ; preds = %loopentry
+       ret void
+}