[WebAssembly] Define the signature for __stack_chk_fail

The WebAssembly backend needs to know the signatures of all runtime
libcall functions. This adds the signature for __stack_chk_fail which was
previously missing.

Also, make the error message for a missing libcall include the name of
the function.

Differential Revision: https://reviews.llvm.org/D59521

Reviewed By: sbc100

llvm-svn: 359505
diff --git a/llvm/test/CodeGen/WebAssembly/stack-protector.ll b/llvm/test/CodeGen/WebAssembly/stack-protector.ll
new file mode 100644
index 0000000..ef0bf94
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/stack-protector.ll
@@ -0,0 +1,30 @@
+; RUN: llc -verify-machineinstrs -mtriple=wasm32-unknown-unknown < %s | FileCheck -check-prefix=WASM32 %s
+
+; WASM32: i32.load        28
+; WASM32-NEXT: i32.sub
+; WASM32-NEXT: br_if           0
+
+; WASM32: __stack_chk_fail
+
+@"\01LC" = internal constant [11 x i8] c"buf == %s\0A\00"		; <[11 x i8]*> [#uses=1]
+
+define void @test(i8* %a) nounwind ssp {
+entry:
+	%a_addr = alloca i8*		; <i8**> [#uses=2]
+	%buf = alloca [8 x i8]		; <[8 x i8]*> [#uses=2]
+  %"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	store i8* %a, i8** %a_addr
+	%buf1 = bitcast [8 x i8]* %buf to i8*		; <i8*> [#uses=1]
+	%0 = load i8*, i8** %a_addr, align 4		; <i8*> [#uses=1]
+	%1 = call i8* @strcpy(i8* %buf1, i8* %0) nounwind		; <i8*> [#uses=0]
+  %buf2 = bitcast [8 x i8]* %buf to i8*		; <i8*> [#uses=1]
+	%2 = call i32 (i8*, ...) @printf(i8* getelementptr ([11 x i8], [11 x i8]* @"\01LC", i32 0, i32 0), i8* %buf2) nounwind		; <i32> [#uses=0]
+	br label %return
+
+return:		; preds = %entry
+	ret void
+}
+
+declare i8* @strcpy(i8*, i8*) nounwind
+
+declare i32 @printf(i8*, ...) nounwind