[WebAssemby] Re-apply r320041: "Support main functions with alternate signatures."

This includes a fix so that it doesn't transform declarations, and it
puts the functionality under control of a command-line option which is off
by default to avoid breaking existing setups.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320196 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 37 insertions, 0 deletions

diff --git a/test/CodeGen/WebAssembly/main-declaration.ll b/test/CodeGen/WebAssembly/main-declaration.ll
new file mode 100644
index 00000000000..4e337850b81
--- /dev/null
+++ b/test/CodeGen/WebAssembly/main-declaration.ll
@@ -0,0 +1,19 @@
+; RUN: llc < %s -asm-verbose=false -wasm-temporary-workarounds=false | FileCheck %s
+
+; Test main functions with alternate signatures.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+declare void @main()
+
+define void @foo() {
+  call void @main()
+  ret void
+}
+
+; CHECK-NOT:   __original_main
+; CHECK-LABEL: foo:
+; CHECK-NEXT:    call main@FUNCTION
+; CHECK-NEXT:    end_function
+; CHECK-NOT:   __original_main
diff --git a/test/CodeGen/WebAssembly/main.ll b/test/CodeGen/WebAssembly/main.ll
new file mode 100644
index 00000000000..c77db8467d8
--- /dev/null
+++ b/test/CodeGen/WebAssembly/main.ll
@@ -0,0 +1,18 @@
+; RUN: llc < %s -asm-verbose=false -wasm-temporary-workarounds=false | FileCheck %s
+
+; Test main functions with alternate signatures.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+define void @main() {
+  ret void
+}
+
+; CHECK-LABEL: .L__original_main:
+; CHECK-NEXT: end_function
+
+; CHECK-LABEL: main:
+; CHECK-NEXT: .param i32, i32
+; CHECK-NEXT: .result i32
+; CHECK:      call .L__original_main@FUNCTION