[PruneEH] Be correct in the face IPO

This fixes one spot I had missed in r265762.  Credit goes to Philip
Reames for spotting this one!

llvm-svn: 283137

llvm/lib/Transforms/IPO/PruneEH.cpp

@@ -90,10 +90,7 @@ static bool runImpl(CallGraphSCC &SCC, CallGraph &CG) {
     if (!F) {
       SCCMightUnwind = true;
       SCCMightReturn = true;
-    } else if (F->isDeclaration() || F->isInterposable()) {
+    } else if (!F->hasExactDefinition()) {
-      // Note: isInterposable (as opposed to hasExactDefinition) is fine above,
-      // since we're not inferring new attributes here, but only using existing,
-      // assumed to be correct, function attributes.
       SCCMightUnwind |= !F->doesNotThrow();
       SCCMightReturn |= !F->doesNotReturn();
     } else {

llvm/test/Transforms/PruneEH/ipo-nounwind.ll

@@ -0,0 +1,43 @@
+; RUN: opt -S -prune-eh < %s | FileCheck %s
+
+declare void @may_throw()
+
+; @callee below may be an optimized form of this function, which can
+; throw at runtime (see r265762 for more details):
+; 
+; define linkonce_odr void @callee(i32* %ptr) noinline {
+; entry:
+;   %val0 = load atomic i32, i32* %ptr unordered, align 4
+;   %val1 = load atomic i32, i32* %ptr unordered, align 4
+;   %cmp = icmp eq i32 %val0, %val1
+;   br i1 %cmp, label %left, label %right
+
+; left:
+;   ret void
+
+; right:
+;   call void @may_throw()
+;   ret void
+; }
+
+define linkonce_odr void @callee(i32* %ptr) noinline {
+  ret void
+}
+
+define i32 @caller(i32* %ptr) personality i32 3 {
+; CHECK-LABEL: @caller(
+; CHECK:  invoke void @callee(i32* %ptr)
+; CHECK-NEXT:          to label %normal unwind label %unwind
+
+entry:
+  invoke void @callee(i32* %ptr)
+          to label %normal unwind label %unwind
+
+normal:
+  ret i32 1
+
+unwind:
+  %res = landingpad { i8*, i32 }
+         cleanup
+  ret i32 2
+}