From e1e520f601f3b0186eab1bdf7df4a54d0c640a3e Mon Sep 17 00:00:00 2001
From: Duncan Sands <baldrick@free.fr>
Date: Sun, 13 Jan 2008 08:02:44 +0000
Subject: [PATCH] When turning a call to a bitcast function into a direct call,
 if this becomes a varargs call then deal correctly with any parameter
 attributes on the newly vararg call arguments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45931 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../Scalar/InstructionCombining.cpp           | 29 +++++++++++--------
 .../2008-01-06-BitCastAttributes.ll           |  3 +-
 .../2008-01-13-NoBitCastAttributes.ll         | 15 ++++++++++
 3 files changed, 33 insertions(+), 14 deletions(-)
 create mode 100644 test/Transforms/InstCombine/2008-01-13-NoBitCastAttributes.ll

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 93fad0a1fae..ea53aec76cb 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -8142,9 +8142,9 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
       return false;   // Cannot transform this return value.
 
     if (!Caller->use_empty() &&
-        !CastInst::isCastable(FT->getReturnType(), OldRetTy) &&
         // void -> non-void is handled specially
-        FT->getReturnType() != Type::VoidTy)
+        FT->getReturnType() != Type::VoidTy &&
+        !CastInst::isCastable(FT->getReturnType(), OldRetTy))
       return false;   // Cannot transform this return value.
 
     if (CallerPAL && !Caller->use_empty()) {
@@ -8200,14 +8200,17 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
       Callee->isDeclaration())
     return false;   // Do not delete arguments unless we have a function body...
 
-  if (FT->getNumParams() < NumActualArgs && FT->isVarArg())
+  if (FT->getNumParams() < NumActualArgs && FT->isVarArg() && CallerPAL)
     // In this case we have more arguments than the new function type, but we
-    // won't be dropping them.  Some of them may have attributes.  If so, we
-    // cannot perform the transform because attributes are not allowed after
-    // the end of the function type.
-    if (CallerPAL && CallerPAL->size() &&
-        CallerPAL->getParamIndex(CallerPAL->size()-1) > FT->getNumParams())
-      return false;
+    // won't be dropping them.  Check that these extra arguments have attributes
+    // that are compatible with being a vararg call argument.
+    for (unsigned i = CallerPAL->size(); i; --i) {
+      if (CallerPAL->getParamIndex(i - 1) <= FT->getNumParams())
+        break;
+      uint16_t PAttrs = CallerPAL->getParamAttrsAtIndex(i - 1);
+      if (PAttrs & ParamAttr::VarArgsIncompatible)
+        return false;
+    }
 
   // Okay, we decided that this is a safe thing to do: go ahead and start
   // inserting cast instructions as necessary...
@@ -8269,10 +8272,12 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
         } else {
           Args.push_back(*AI);
         }
-      }
 
-      // No need to add parameter attributes - we already checked that there
-      // aren't any.
+        // Add any parameter attributes.
+        uint16_t PAttrs = CallerPAL ? CallerPAL->getParamAttrs(i + 1) : 0;
+        if (PAttrs)
+          attrVec.push_back(ParamAttrsWithIndex::get(i + 1, PAttrs));
+      }
     }
 
   if (FT->getReturnType() == Type::VoidTy)
diff --git a/test/Transforms/InstCombine/2008-01-06-BitCastAttributes.ll b/test/Transforms/InstCombine/2008-01-06-BitCastAttributes.ll
index 5bb8875961d..99c34907c00 100644
--- a/test/Transforms/InstCombine/2008-01-06-BitCastAttributes.ll
+++ b/test/Transforms/InstCombine/2008-01-06-BitCastAttributes.ll
@@ -1,4 +1,4 @@
-; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep bitcast | count 2
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep bitcast
 
 define void @a() {
 	ret void
@@ -17,7 +17,6 @@ define void @g(i32* %y) {
 	call <2 x i32> bitcast (i32 (i32*)* @b to <2 x i32> (i32*)*)( i32* inreg  null )		; <<2 x i32>>:1 [#uses=0]
 	%x = call i64 bitcast (i32 (i32*)* @b to i64 (i32)*)( i32 0 )		; <i64> [#uses=0]
 	call void bitcast (void (...)* @c to void (i32)*)( i32 0 )
-	call i32 bitcast (i32 (i32*)* @b to i32 (i32)*)( i32 zeroext  0 )		; <i32>:2 [#uses=0]
 	call void bitcast (void (...)* @c to void (i32)*)( i32 zeroext  0 )
 	ret void
 }
diff --git a/test/Transforms/InstCombine/2008-01-13-NoBitCastAttributes.ll b/test/Transforms/InstCombine/2008-01-13-NoBitCastAttributes.ll
new file mode 100644
index 00000000000..d791d7be26e
--- /dev/null
+++ b/test/Transforms/InstCombine/2008-01-13-NoBitCastAttributes.ll
@@ -0,0 +1,15 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep bitcast | count 2
+
+define i32 @b(i32* inreg  %x) signext  {
+	ret i32 0
+}
+
+define void @c(...) {
+	ret void
+}
+
+define void @g(i32* %y) {
+	call i32 bitcast (i32 (i32*)* @b to i32 (i32)*)( i32 zeroext  0 )		; <i32>:2 [#uses=0]
+	call void bitcast (void (...)* @c to void (i32*)*)( i32* sret  null )
+	ret void
+}
-- 
2.34.1