CGSCC should not treat intrinsic calls like function calls (PR21403)

Make the handling of calls to intrinsics in CGSCC consistent: 
they are not treated like regular function calls because they
are never lowered to function calls.

Without this patch, we can get dangling pointer asserts from
the subsequent loop that processes callsites because it already
ignores intrinsics.

See http://llvm.org/bugs/show_bug.cgi?id=21403 for more details / discussion.

Differential Revision: http://reviews.llvm.org/D6124

llvm-svn: 221802

lib/Analysis/IPA/CallGraphSCCPass.cpp

@@ -243,7 +243,14 @@ bool CGPassManager::RefreshCallGraph(CallGraphSCC &CurSCC,
       
       assert(!CallSites.count(I->first) &&
              "Call site occurs in node multiple times");
-      CallSites.insert(std::make_pair(I->first, I->second));
+      
+      CallSite CS(I->first);
+      if (CS) {
+        Function *Callee = CS.getCalledFunction();
+        // Ignore intrinsics because they're not really function calls.
+        if (!Callee || !(Callee->isIntrinsic()))
+          CallSites.insert(std::make_pair(I->first, I->second));
+      }
       ++I;
     }
     

test/Transforms/InstCombine/no_cgscc_assert.ll

@@ -0,0 +1,19 @@
+; RUN: opt < %s -inline -instcombine -S | FileCheck %s
+
+; PR21403: http://llvm.org/bugs/show_bug.cgi?id=21403
+; When the call to sqrtf is replaced by an intrinsic call to fabs,
+; it should not cause a problem in CGSCC. 
+
+define float @bar(float %f) #0 {
+  %mul = fmul fast float %f, %f
+  %call1 = call float @sqrtf(float %mul) #0
+  ret float %call1
+
+; CHECK-LABEL: @bar(
+; CHECK-NEXT: call float @llvm.fabs.f32
+; CHECK-NEXT: ret float
+}
+
+declare float @sqrtf(float) #0
+
+attributes #0 = { readnone "unsafe-fp-math"="true" }