From 0d4e33d2114e074fa3d84b85bf33df706bb3e5f6 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dan433584@gmail.com>
Date: Fri, 20 Jan 2017 20:50:29 +0000
Subject: [PATCH] [WebAssembly] Don't create bitcast-wrappers for varargs.

WebAssembly varargs functions use a significantly different ABI than
non-varargs functions, and the current code in
WebAssemblyFixFunctionBitcasts doesn't handle that difference. For now,
just avoid creating wrapper functions in the presence of varargs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292645 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../WebAssemblyFixFunctionBitcasts.cpp          |  5 +++++
 test/CodeGen/WebAssembly/function-bitcasts.ll   | 17 +++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp b/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
index adf904ee026..cdbd9ea4b09 100644
--- a/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
+++ b/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
@@ -148,6 +148,11 @@ bool FixFunctionBitcasts::runOnModule(Module &M) {
     if (!Ty)
       continue;
 
+    // Wasm varargs are not ABI-compatible with non-varargs. Just ignore
+    // such casts for now.
+    if (Ty->isVarArg() || F->isVarArg())
+      continue;
+
     auto Pair = Wrappers.insert(std::make_pair(std::make_pair(F, Ty), nullptr));
     if (Pair.second)
       Pair.first->second = CreateWrapper(F, Ty);
diff --git a/test/CodeGen/WebAssembly/function-bitcasts.ll b/test/CodeGen/WebAssembly/function-bitcasts.ll
index e4f8f3fb6ca..9cafdd5bc2c 100644
--- a/test/CodeGen/WebAssembly/function-bitcasts.ll
+++ b/test/CodeGen/WebAssembly/function-bitcasts.ll
@@ -22,6 +22,15 @@ target triple = "wasm32-unknown-unknown"
 ; CHECK-NEXT: call        foo3@FUNCTION{{$}}
 ; CHECK-NEXT: .endfunc
 
+; CHECK-LABEL: test_varargs:
+; CHECK-NEXT: .local      i32
+; CHECK:      store
+; CHECK:      i32.const   $push[[L3:[0-9]+]]=, 0{{$}}
+; CHECK-NEXT: call        vararg@FUNCTION, $pop[[L3]]{{$}}
+; CHECK-NEXT: i32.const   $push[[L4:[0-9]+]]=, 0{{$}}
+; CHECK-NEXT: i32.store   0($[[L5:[0-9]+]]), $pop[[L4]]{{$}}
+; CHECK-NEXT: call        plain@FUNCTION, $[[L5]]{{$}}
+
 ; CHECK-LABEL: .Lbitcast:
 ; CHECK-NEXT: .local      i32
 ; CHECK-NEXT: call        has_i32_arg@FUNCTION, $0{{$}}
@@ -45,6 +54,8 @@ target triple = "wasm32-unknown-unknown"
 
 declare void @has_i32_arg(i32)
 declare i32 @has_i32_ret()
+declare void @vararg(...)
+declare void @plain(i32)
 
 declare void @foo0()
 declare void @foo1()
@@ -70,3 +81,9 @@ entry:
 
   ret void
 }
+
+define void @test_varargs() {
+  call void bitcast (void (...)* @vararg to void (i32)*)(i32 0)
+  call void (...) bitcast (void (i32)* @plain to void (...)*)(i32 0)
+  ret void
+}
-- 
2.40.0