[PATCH] D57538: [WebAssembly] MC: Fix type of function aliases

[Sam Clegg via Phabricator via llvm-commits]

sbc100 updated this revision to Diff 184655.
sbc100 added a comment.
Herald added a project: LLVM.

- Handle issue in AsmPrinter so MCSymbol has correct type


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57538/new/

https://reviews.llvm.org/D57538

Files:
  lib/CodeGen/AsmPrinter/AsmPrinter.cpp
  test/MC/WebAssembly/function-alias.ll


Index: test/MC/WebAssembly/function-alias.ll
===================================================================
--- /dev/null
+++ test/MC/WebAssembly/function-alias.ll
@@ -0,0 +1,29 @@
+; RUN: llc -filetype=obj %s -o - | llvm-readobj -symbols | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+ at foo = alias i8, bitcast (i8* ()* @func to i8*)
+ at bar = alias i8* (), i8* ()* @func
+
+define i8* @func() {
+  ret i8* @foo;
+}
+
+; CHECK:      Symbols [
+; CHECK-NEXT:   Symbol {
+; CHECK-NEXT:     Name: func
+; CHECK-NEXT:     Type: FUNCTION (0x0)
+; CHECK-NEXT:     Flags: 0x0
+; CHECK-NEXT:   }
+; CHECK-NEXT:   Symbol {
+; CHECK-NEXT:     Name: foo
+; CHECK-NEXT:     Type: FUNCTION (0x0)
+; CHECK-NEXT:     Flags: 0x0
+; CHECK-NEXT:   }
+; CHECK-NEXT:   Symbol {
+; CHECK-NEXT:     Name: bar
+; CHECK-NEXT:     Type: FUNCTION (0x0)
+; CHECK-NEXT:     Flags: 0x0
+; CHECK-NEXT:   }
+; CHECK-NEXT: ]
Index: lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1337,9 +1337,20 @@
   else
     assert(GIS.hasLocalLinkage() && "Invalid alias or ifunc linkage");
 
+  bool isFunction = GIS.getType()->getPointerElementType()->isFunctionTy();
+
+  // Treat bitcasts of functions as functions also. This is important at least
+  // on WebAssembly where object and function addresses can't alias each other.
+  if (!isFunction)
+    if (auto *CE = dyn_cast<ConstantExpr>(GIS.getIndirectSymbol()))
+      if (CE->getOpcode() == Instruction::BitCast)
+        isFunction =
+          CE->getOperand(0)->getType()->getPointerElementType()->isFunctionTy();
+
+
   // Set the symbol type to function if the alias has a function type.
   // This affects codegen when the aliasee is not a function.
-  if (GIS.getType()->getPointerElementType()->isFunctionTy()) {
+  if (isFunction) {
     OutStreamer->EmitSymbolAttribute(Name, MCSA_ELF_TypeFunction);
     if (isa<GlobalIFunc>(GIS))
       OutStreamer->EmitSymbolAttribute(Name, MCSA_ELF_TypeIndFunction);


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