[llvm] r373929 - Fix Calling Convention through aliases

[Erich Keane via llvm-commits]

Author: erichkeane
Date: Mon Oct  7 10:28:03 2019
New Revision: 373929

URL: http://llvm.org/viewvc/llvm-project?rev=373929&view=rev
Log:
Fix Calling Convention through aliases

r369697 changed the behavior of stripPointerCasts to no longer include
aliases.  However, the code in CGDeclCXX.cpp's createAtExitStub counted
on the looking through aliases to properly set the calling convention of
a call.

The result of the change was that the calling convention mismatch of the
call would be replaced with a llvm.trap, causing a runtime crash.

Differential Revision: https://reviews.llvm.org/D68584

Modified:
    llvm/trunk/include/llvm/IR/Value.h
    llvm/trunk/lib/IR/Value.cpp

Modified: llvm/trunk/include/llvm/IR/Value.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Value.h?rev=373929&r1=373928&r2=373929&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/Value.h (original)
+++ llvm/trunk/include/llvm/IR/Value.h Mon Oct  7 10:28:03 2019
@@ -523,6 +523,16 @@ public:
         static_cast<const Value *>(this)->stripPointerCasts());
   }
 
+  /// Strip off pointer casts, all-zero GEPs, address space casts, and aliases.
+  ///
+  /// Returns the original uncasted value.  If this is called on a non-pointer
+  /// value, it returns 'this'.
+  const Value *stripPointerCastsAndAliases() const;
+  Value *stripPointerCastsAndAliases() {
+    return const_cast<Value *>(
+        static_cast<const Value *>(this)->stripPointerCastsAndAliases());
+  }
+
   /// Strip off pointer casts, all-zero GEPs and address space casts
   /// but ensures the representation of the result stays the same.
   ///

Modified: llvm/trunk/lib/IR/Value.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Value.cpp?rev=373929&r1=373928&r2=373929&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Value.cpp (original)
+++ llvm/trunk/lib/IR/Value.cpp Mon Oct  7 10:28:03 2019
@@ -455,6 +455,7 @@ namespace {
 // Various metrics for how much to strip off of pointers.
 enum PointerStripKind {
   PSK_ZeroIndices,
+  PSK_ZeroIndicesAndAliases,
   PSK_ZeroIndicesSameRepresentation,
   PSK_ZeroIndicesAndInvariantGroups,
   PSK_InBoundsConstantIndices,
@@ -475,6 +476,7 @@ static const Value *stripPointerCastsAnd
     if (auto *GEP = dyn_cast<GEPOperator>(V)) {
       switch (StripKind) {
       case PSK_ZeroIndices:
+      case PSK_ZeroIndicesAndAliases:
       case PSK_ZeroIndicesSameRepresentation:
       case PSK_ZeroIndicesAndInvariantGroups:
         if (!GEP->hasAllZeroIndices())
@@ -497,6 +499,8 @@ static const Value *stripPointerCastsAnd
       // TODO: If we know an address space cast will not change the
       //       representation we could look through it here as well.
       V = cast<Operator>(V)->getOperand(0);
+    } else if (StripKind == PSK_ZeroIndicesAndAliases && isa<GlobalAlias>(V)) {
+      V = cast<GlobalAlias>(V)->getAliasee();
     } else {
       if (const auto *Call = dyn_cast<CallBase>(V)) {
         if (const Value *RV = Call->getReturnedArgOperand()) {
@@ -526,6 +530,10 @@ const Value *Value::stripPointerCasts()
   return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this);
 }
 
+const Value *Value::stripPointerCastsAndAliases() const {
+  return stripPointerCastsAndOffsets<PSK_ZeroIndicesAndAliases>(this);
+}
+
 const Value *Value::stripPointerCastsSameRepresentation() const {
   return stripPointerCastsAndOffsets<PSK_ZeroIndicesSameRepresentation>(this);
 }