change instcombine to not turn a call to non-varargs bitcast of

function prototype into a call to a varargs prototype.  We do
allow the xform if we have a definition, but otherwise we don't
want to risk that we're changing the abi in a subtle way.  On
X86-64, for example, varargs require passing stuff in %al.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126363 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 30 insertions, 18 deletions

diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 8449f7b..0e46450 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -953,10 +953,19 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
     if (Callee->isDeclaration() && !isConvertible) return false;
   }
 
-  if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
-      Callee->isDeclaration())
-    return false;   // Do not delete arguments unless we have a function body.
-
+  if (Callee->isDeclaration()) {
+    // Do not delete arguments unless we have a function body.
+    if (FT->getNumParams() < NumActualArgs && !FT->isVarArg())
+      return false;
+
+    // If the callee is just a declaration, don't change the varargsness of the
+    // call.  We don't want to introduce a varargs call where one doesn't
+    // already exist.
+    const PointerType *APTy = cast<PointerType>(CS.getCalledValue()->getType());
+    if (FT->isVarArg()!=cast<FunctionType>(APTy->getElementType())->isVarArg())
+      return false;
+  }
+      
   if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
       !CallerPAL.isEmpty())
     // In this case we have more arguments than the new function type, but we
@@ -970,8 +979,9 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
         return false;
     }
 
+  
   // Okay, we decided that this is a safe thing to do: go ahead and start
-  // inserting cast instructions as necessary...
+  // inserting cast instructions as necessary.
   std::vector<Value*> Args;
   Args.reserve(NumActualArgs);
   SmallVector<AttributeWithIndex, 8> attrVec;
diff --git a/test/Transforms/InstCombine/2003-11-13-ConstExprCastCall.ll b/test/Transforms/InstCombine/2003-11-13-ConstExprCastCall.ll
deleted file mode 100644
index fdb8fd9..0000000
--- a/test/Transforms/InstCombine/2003-11-13-ConstExprCastCall.ll
+++ /dev/null
@@ -1,12 +0,0 @@
-; RUN: opt < %s -instcombine -S | FileCheck %s
-target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128"
-
-declare void @free(i8*)
-
-define void @test(i32* %X) {
-        call void (...)* bitcast (void (i8*)* @free to void (...)*)( i32* %X )          ; <i32>:1 [#uses=0]
-; CHECK: %tmp = bitcast i32* %X to i8*
-; CHECK: call void @free(i8* %tmp)
-        ret void
-; CHECK: ret void
-}
diff --git a/test/Transforms/InstCombine/call.ll b/test/Transforms/InstCombine/call.ll
index c256724..2ef8dc0 100644
--- a/test/Transforms/InstCombine/call.ll
+++ b/test/Transforms/InstCombine/call.ll
@@ -32,7 +32,7 @@ define i32 @test2(i32 %A) {
 
 ; Resolving this should insert a cast from sbyte to int, following the C 
 ; promotion rules.
-declare void @test3a(i8, ...)
+define void @test3a(i8, ...) {unreachable }
 
 define void @test3(i8 %A, i8 %B) {
         call void bitcast (void (i8, ...)* @test3a to void (i8, i8)*)( i8 %A, i8 %B 
@@ -116,3 +116,17 @@ try.handler:                                      ; preds = %entry
 ; CHECK: @test8() {
 ; CHECK-NEXT: invoke void @test8a()
 
+
+
+; Don't turn this into a direct call, because test9x is just a prototype and 
+; doing so will make it varargs.
+; rdar://9038601
+declare i8* @test9x(i8*, i8*, ...) noredzone
+define i8* @test9(i8* %arg, i8* %tmp3) nounwind ssp noredzone {
+entry:
+  %call = call i8* bitcast (i8* (i8*, i8*, ...)* @test9x to i8* (i8*, i8*)*)(i8* %arg, i8* %tmp3) noredzone
+  ret i8* %call
+; CHECK: @test9(
+; CHECK: call i8* bitcast
+}
+