From f960f4d0da0bcdf187092f6961664375a27bccbf Mon Sep 17 00:00:00 2001
From: Prakalp Srivastava <prakalps@gmail.com>
Date: Tue, 30 Jun 2015 19:12:06 -0500
Subject: [PATCH] Added a patch approved in future llvm branches which stop
argument promotion for variagic functions. This was required to stop auto
promotion of arguments in __visc__ calls
---
llvm/lib/Transforms/IPO/ArgumentPromotion.cpp | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
index e6fa4edf61..483c363dd1 100644
--- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -125,6 +125,13 @@ CallGraphNode *ArgPromotion::PromoteArguments(CallGraphNode *CGN) {
// Make sure that it is local to this module.
if (!F || !F->hasLocalLinkage()) return 0;
+ // Don't promote arguments for variadic functions. Adding, removing, or
+ // changing non-pack parameters can change the classification of pack
+ // parameters. Frontends encode that classification at the call site in the
+ // IR, while in the callee the classification is determined dynamically
+ // on the number of registers consumed so far.
+ if (F->isVarArg()) return nullptr;
+
// First check: see if there are any pointer arguments! If not, quick exit.
SmallVector<std::pair<Argument*, unsigned>, 16> PointerArgs;
unsigned ArgNo = 0;
--
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