[PATCH] D20612: Analysis: Do not create call graph nodes for intrinsic functions.

[Peter Collingbourne via llvm-commits]

pcc created this revision.
pcc added reviewers: dberlin, chandlerc, hfinkel, reames, sanjoy.
pcc added subscribers: llvm-commits, krasin.

Intrinsic functions do not participate in the call graph, so there is no
need to create call graph nodes for them.

This has the effect of inhibiting SCC-based function attribute inference for
intrinsic functions, which was previously incorrectly setting the readnone
attribute on the llvm.assume intrinsic as a result of propagating the AA
result introduced in D19730 to its attributes.

http://reviews.llvm.org/D20612

Files:
  lib/Analysis/CallGraph.cpp
  lib/Transforms/IPO/PruneEH.cpp
  test/Transforms/FunctionAttrs/assume.ll

Index: test/Transforms/FunctionAttrs/assume.ll
===================================================================
--- /dev/null
+++ test/Transforms/FunctionAttrs/assume.ll
@@ -0,0 +1,4 @@
+; RUN: opt -S -o - -functionattrs %s | FileCheck %s
+
+; CHECK-NOT: readnone
+declare void @llvm.assume(i1)
Index: lib/Transforms/IPO/PruneEH.cpp
===================================================================
--- lib/Transforms/IPO/PruneEH.cpp
+++ lib/Transforms/IPO/PruneEH.cpp
@@ -134,11 +134,14 @@
             bool InstMightUnwind = true;
             if (const auto *CI = dyn_cast<CallInst>(&I)) {
               if (Function *Callee = CI->getCalledFunction()) {
-                CallGraphNode *CalleeNode = CG[Callee];
-                // If the callee is outside our current SCC then we may throw
-                // because it might.  If it is inside, do nothing.
-                if (SCCNodes.count(CalleeNode) > 0)
-                  InstMightUnwind = false;
+                // The call graph does not contain intrinsics.
+                if (!Callee->isIntrinsic()) {
+                  CallGraphNode *CalleeNode = CG[Callee];
+                  // If the callee is outside our current SCC then we may throw
+                  // because it might.  If it is inside, do nothing.
+                  if (SCCNodes.count(CalleeNode) > 0)
+                    InstMightUnwind = false;
+                }
               }
             }
             SCCMightUnwind |= InstMightUnwind;
Index: lib/Analysis/CallGraph.cpp
===================================================================
--- lib/Analysis/CallGraph.cpp
+++ lib/Analysis/CallGraph.cpp
@@ -55,6 +55,9 @@
 }
 
 void CallGraph::addToCallGraph(Function *F) {
+  if (F->isIntrinsic())
+    return;
+
   CallGraphNode *Node = getOrInsertFunction(F);
 
   // If this function has external linkage, anything could call it.
@@ -76,7 +79,7 @@
 
   // If this function is not defined in this translation unit, it could call
   // anything.
-  if (F->isDeclaration() && !F->isIntrinsic())
+  if (F->isDeclaration())
     Node->addCalledFunction(CallSite(), CallsExternalNode.get());
 
   // Look for calls by this function.


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