[llvm] r358793 - [WebAssembly] FastISel: Don't fallback to SelectionDAG after BuildMI in selectCall

[Sam Clegg via llvm-commits]

Author: sbc
Date: Fri Apr 19 15:43:32 2019
New Revision: 358793

URL: http://llvm.org/viewvc/llvm-project?rev=358793&view=rev
Log:
[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

Modified:
    llvm/trunk/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
    llvm/trunk/test/CodeGen/WebAssembly/call-pic.ll

Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyFastISel.cpp?rev=358793&r1=358792&r2=358793&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyFastISel.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyFastISel.cpp Fri Apr 19 15:43:32 2019
@@ -851,6 +851,13 @@ bool WebAssemblyFastISel::selectCall(con
     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(con
 
   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);

Modified: llvm/trunk/test/CodeGen/WebAssembly/call-pic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/call-pic.ll?rev=358793&r1=358792&r2=358793&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/call-pic.ll (original)
+++ llvm/trunk/test/CodeGen/WebAssembly/call-pic.ll Fri Apr 19 15:43:32 2019
@@ -8,6 +8,11 @@ declare i32 @bar()
 declare hidden i32 @hidden_function()
 
 @indirect_func = global i32 ()* @foo
+ at 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 $push[[L0:[0-9]+]]=, bar at GOT{{$}}