The method of doing the matching with a 'select' instruction was wrong. The

original code was matching like this:

	if (match(A, m_Not(m_Value(B))))

B was already matched as a 'select' instruction. However, this isn't matching
what we think it's matching. It would match B as a 'Value', so basically
anything would match to it. In this case, a Constant matched. B was replaced
with a constant representation. And then the wrong value would be used in the
SelectInst::Create statement, causing a crash.

After thinking on this for a moment, and after Nick L. told me how the pattern
matching stuff was supposed to work, the solution was to match NOT an m_Value,
but an m_Select.

llvm-svn: 58946

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/test/FrontendC/2008-11-08-InstCombineSelect.c b/llvm/test/FrontendC/2008-11-08-InstCombineSelect.c
new file mode 100644
index 00000000000..70c8d3a2248
--- /dev/null
+++ b/llvm/test/FrontendC/2008-11-08-InstCombineSelect.c
@@ -0,0 +1,17 @@
+// RUN: %llvmgcc %s -S -emit-llvm -O2 -o -
+// PR3028
+
+int g_187;
+int g_204;
+int g_434;
+
+int func_89 (void)
+{
+  return 1;
+}
+
+void func_20 (int p_22)
+{
+  if (1 & p_22 | g_204 & (1 < g_187) - func_89 ())
+    g_434 = 1;
+}