From a27252794e0785af0eff7367ac9d57d91dffe944 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc@chromium.org>
Date: Fri, 19 Apr 2019 22:43:32 +0000
Subject: [PATCH] [WebAssembly] FastISel: Don't fallback to SelectionDAG after
 BuildMI in selectCall

My understanding is that once BuildMI has been called we can't fallback
to SelectionDAG.

This change moves the fallback for when getRegForValue() fails for
that target of an indirect call.  This was failing in -fPIC mode when
the callee is GlobalValue.

Add a test case that tickles this.

Differential Revision: https://reviews.llvm.org/D60908

llvm-svn: 358793
---
 llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp | 15 +++++++++------
 llvm/test/CodeGen/WebAssembly/call-pic.ll           | 15 +++++++++++++++
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
index 1705748..2d9aae7a 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
@@ -851,6 +851,13 @@ bool WebAssemblyFastISel::selectCall(const Instruction *I) {
     Args.push_back(Reg);
   }
 
+  unsigned CalleeReg = 0;
+  if (!IsDirect) {
+    CalleeReg = getRegForValue(Call->getCalledValue());
+    if (!CalleeReg)
+      return false;
+  }
+
   auto MIB = BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Opc));
 
   if (!IsVoid)
@@ -858,12 +865,8 @@ bool WebAssemblyFastISel::selectCall(const Instruction *I) {
 
   if (IsDirect)
     MIB.addGlobalAddress(Func);
-  else {
-    unsigned Reg = getRegForValue(Call->getCalledValue());
-    if (Reg == 0)
-      return false;
-    MIB.addReg(Reg);
-  }
+  else
+    MIB.addReg(CalleeReg);
 
   for (unsigned ArgReg : Args)
     MIB.addReg(ArgReg);
diff --git a/llvm/test/CodeGen/WebAssembly/call-pic.ll b/llvm/test/CodeGen/WebAssembly/call-pic.ll
index b50f96d..b319ea4 100644
--- a/llvm/test/CodeGen/WebAssembly/call-pic.ll
+++ b/llvm/test/CodeGen/WebAssembly/call-pic.ll
@@ -8,6 +8,11 @@ declare i32 @bar()
 declare hidden i32 @hidden_function()
 
 @indirect_func = global i32 ()* @foo
+@alias_func = hidden alias i32 (), i32 ()* @local_function
+
+define i32 @local_function() {
+  ret i32 1
+}
 
 define void @call_indirect_func() {
 ; CHECK-LABEL: call_indirect_func:
@@ -31,6 +36,16 @@ define void @call_direct() {
   ret void
 }
 
+define void @call_alias_func() {
+; CHECK-LABEL: call_alias_func:
+; CHECK: .functype call_alias_func () -> ()
+; CHECK-NEXT: i32.call $push0=, alias_func
+; CHECK-NEXT: drop $pop0{{$}}
+; CHECK-NEXT: return{{$}}
+  %call = call i32 @alias_func()
+  ret void
+}
+
 define i8* @get_function_address() {
 ; CHECK-LABEL: get_function_address:
 ; CHECK:       global.get $push[[L0:[0-9]+]]=, bar@GOT{{$}}
-- 
2.7.4