[WebAssembly] Emit type signatures for declared functions

Under emscripten, C code can take the address of a function implemented
in Javascript (which is exposed via an import in wasm). Because imports
do not have linear memory address in wasm, we need to generate a thunk
to be the target of the indirect call; it call the import directly.

To make this possible, LLVM needs to emit the type signatures for these
functions, because they may not be called directly or referred to other
than where the address is taken.

This uses s new .s directive (.functype) which specifies the signature.

Differential Revision: http://reviews.llvm.org/D20891

llvm-svn: 271599

1 files changed, 70 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/WebAssembly/indirect-import.ll b/llvm/test/CodeGen/WebAssembly/indirect-import.ll
new file mode 100644
index 00000000000..fad7c0b23b6
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/indirect-import.ll
@@ -0,0 +1,70 @@
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -verify-machineinstrs | FileCheck %s
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -verify-machineinstrs -fast-isel | FileCheck %s
+
+; ModuleID = 'test/dot_s/indirect-import.c'
+source_filename = "test/dot_s/indirect-import.c"
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32"
+
+%struct.big = type { float, double, i32 }
+
+; Function Attrs: nounwind
+; CHECK: bar:
+define hidden i32 @bar() #0 {
+entry:
+  %fd = alloca float (double)*, align 4
+  %vj = alloca void (i64)*, align 4
+  %v = alloca void ()*, align 4
+  %ijidf = alloca i32 (i64, i32, double, float)*, align 4
+  %vs = alloca void (%struct.big*)*, align 4
+  %s = alloca void (%struct.big*)*, align 4
+
+; CHECK: i32.const       {{.+}}=, extern_fd@FUNCTION
+  store float (double)* @extern_fd, float (double)** %fd, align 4
+; CHECK: i32.const       {{.+}}=, extern_vj@FUNCTION
+  store void (i64)* @extern_vj, void (i64)** %vj, align 4
+  %0 = load void (i64)*, void (i64)** %vj, align 4
+  call void %0(i64 1)
+
+; CHECK: i32.const       {{.+}}=, extern_v@FUNCTION
+  store void ()* @extern_v, void ()** %v, align 4
+  %1 = load void ()*, void ()** %v, align 4
+  call void %1()
+
+; CHECK: i32.const       {{.+}}=, extern_ijidf@FUNCTION
+  store i32 (i64, i32, double, float)* @extern_ijidf, i32 (i64, i32, double, float)** %ijidf, align 4
+  %2 = load i32 (i64, i32, double, float)*, i32 (i64, i32, double, float)** %ijidf, align 4
+  %call = call i32 %2(i64 1, i32 2, double 3.000000e+00, float 4.000000e+00)
+
+; CHECK: i32.const       {{.+}}=, extern_struct@FUNCTION
+  store void (%struct.big*)* @extern_struct, void (%struct.big*)** %vs, align 4
+
+; CHECK: i32.const       {{.+}}=, extern_sret@FUNCTION
+  store void (%struct.big*)* @extern_sret, void (%struct.big*)** %s, align 4
+  %3 = load float (double)*, float (double)** %fd, align 4
+  %4 = ptrtoint float (double)* %3 to i32
+  ret i32 %4
+}
+
+declare float @extern_fd(double) #1
+
+declare void @extern_vj(i64) #1
+
+declare void @extern_v() #1
+
+declare i32 @extern_ijidf(i64, i32, double, float) #1
+
+declare void @extern_struct(%struct.big* byval align 8) #1
+
+declare void @extern_sret(%struct.big* sret) #1
+
+attributes #0 = { nounwind "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+
+; CHECK: .functype       extern_fd, f32, f64
+; CHECK: .functype       extern_vj, void, i64
+; CHECK: .functype       extern_v, void
+; CHECK: .functype       extern_ijidf, i32, i64, i32, f64, f32
+; CHECK: .functype       extern_struct, void, i32
+; CHECK: .functype       extern_sret, void, i32