From b465aa0504729d35038a454148cb359d9d3a4bff Mon Sep 17 00:00:00 2001
From: Dan Gohman <dan433584@gmail.com>
Date: Wed, 8 Nov 2017 19:18:08 +0000
Subject: [WebAssembly] Revise the strategy for inline asm.

Previously, an "r" constraint would mean the compiler provides a value
on WebAssembly's operand stack. This was tricky to use properly,
particularly since it isn't possible to declare a new local from within
an inline asm string.

With this patch, "r" provides the value in a WebAssembly local, and the
local index is provided to the inline asm string. This requires inline
asm to use get_local and set_local to read the register. This does
potentially result in larger code size, however inline asm should
hopefully be quite rare in WebAssembly.

This also means that the "m" constraint can no longer be supported, as
WebAssembly has nothing like a "memory operand" that includes an
implicit get_local.

This fixes PR34599 for the wasm32-unknown-unknown-wasm target (though
not for the ELF target).

llvm-svn: 317707
---
 llvm/test/CodeGen/WebAssembly/inline-asm.ll | 56 +++++++++++++++++------------
 1 file changed, 33 insertions(+), 23 deletions(-)

(limited to 'llvm/test/CodeGen/WebAssembly/inline-asm.ll')

diff --git a/llvm/test/CodeGen/WebAssembly/inline-asm.ll b/llvm/test/CodeGen/WebAssembly/inline-asm.ll
index 56576305d9e..760b0ad0de6 100644
--- a/llvm/test/CodeGen/WebAssembly/inline-asm.ll
+++ b/llvm/test/CodeGen/WebAssembly/inline-asm.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals -no-integrated-as | FileCheck %s
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -no-integrated-as | FileCheck %s
 
 ; Test basic inline assembly. Pass -no-integrated-as since these aren't
 ; actually valid assembly syntax.
@@ -10,33 +10,24 @@ target triple = "wasm32-unknown-unknown-wasm"
 ; CHECK-NEXT: .param i32{{$}}
 ; CHECK-NEXT: .result i32{{$}}
 ; CHECK-NEXT: #APP{{$}}
-; CHECK-NEXT: # $0 = aaa($0){{$}}
+; CHECK-NEXT: # 0 = aaa(0){{$}}
 ; CHECK-NEXT: #NO_APP{{$}}
-; CHECK-NEXT: return $0{{$}}
+; CHECK-NEXT: get_local $push0=, 0{{$}}
+; CHECK-NEXT: return $pop0{{$}}
 define i32 @foo(i32 %r) {
 entry:
   %0 = tail call i32 asm sideeffect "# $0 = aaa($1)", "=r,r"(i32 %r) #0, !srcloc !0
   ret i32 %0
 }
 
-; CHECK-LABEL: bar:
-; CHECK-NEXT: .param i32, i32{{$}}
-; CHECK-NEXT: #APP{{$}}
-; CHECK-NEXT: # 0($1) = bbb(0($0)){{$}}
-; CHECK-NEXT: #NO_APP{{$}}
-; CHECK-NEXT: return{{$}}
-define void @bar(i32* %r, i32* %s) {
-entry:
-  tail call void asm sideeffect "# $0 = bbb($1)", "=*m,*m"(i32* %s, i32* %r) #0, !srcloc !1
-  ret void
-}
-
 ; CHECK-LABEL: imm:
 ; CHECK-NEXT: .result i32{{$}}
+; CHECK-NEXT: .local i32{{$}}
 ; CHECK-NEXT: #APP{{$}}
-; CHECK-NEXT: # $0 = ccc(42){{$}}
+; CHECK-NEXT: # 0 = ccc(42){{$}}
 ; CHECK-NEXT: #NO_APP{{$}}
-; CHECK-NEXT: return $0{{$}}
+; CHECK-NEXT: get_local $push0=, 0{{$}}
+; CHECK-NEXT: return $pop0{{$}}
 define i32 @imm() {
 entry:
   %0 = tail call i32 asm sideeffect "# $0 = ccc($1)", "=r,i"(i32 42) #0, !srcloc !2
@@ -47,9 +38,10 @@ entry:
 ; CHECK-NEXT: .param i64{{$}}
 ; CHECK-NEXT: .result i64{{$}}
 ; CHECK-NEXT: #APP{{$}}
-; CHECK-NEXT: # $0 = aaa($0){{$}}
+; CHECK-NEXT: # 0 = aaa(0){{$}}
 ; CHECK-NEXT: #NO_APP{{$}}
-; CHECK-NEXT: return $0{{$}}
+; CHECK-NEXT: get_local $push0=, 0{{$}}
+; CHECK-NEXT: return $pop0{{$}}
 define i64 @foo_i64(i64 %r) {
 entry:
   %0 = tail call i64 asm sideeffect "# $0 = aaa($1)", "=r,r"(i64 %r) #0, !srcloc !0
@@ -57,16 +49,20 @@ entry:
 }
 
 ; CHECK-LABEL: X_i16:
-; CHECK: foo $1{{$}}
-; CHECK: i32.store16 0($0), $1{{$}}
+; CHECK: foo 1{{$}}
+; CHECK: get_local $push[[S0:[0-9]+]]=, 0{{$}}
+; CHECK-NEXT: get_local $push[[S1:[0-9]+]]=, 1{{$}}
+; CHECK-NEXT: i32.store16 0($pop[[S0]]), $pop[[S1]]{{$}}
 define void @X_i16(i16 * %t) {
   call void asm sideeffect "foo $0", "=*X,~{dirflag},~{fpsr},~{flags},~{memory}"(i16* %t)
   ret void
 }
 
 ; CHECK-LABEL: X_ptr:
-; CHECK: foo $1{{$}}
-; CHECK: i32.store 0($0), $1{{$}}
+; CHECK: foo 1{{$}}
+; CHECK: get_local $push[[S0:[0-9]+]]=, 0{{$}}
+; CHECK-NEXT: get_local $push[[S1:[0-9]+]]=, 1{{$}}
+; CHECK-NEXT: i32.store 0($pop[[S0]]), $pop[[S1]]{{$}}
 define void @X_ptr(i16 ** %t) {
   call void asm sideeffect "foo $0", "=*X,~{dirflag},~{fpsr},~{flags},~{memory}"(i16** %t)
   ret void
@@ -87,6 +83,20 @@ define void @varname() {
   ret void
 }
 
+; CHECK-LABEL: r_constraint
+; CHECK:      i32.const $push[[S0:[0-9]+]]=, 0{{$}}
+; CHECK-NEXT: set_local [[L0:[0-9]+]], $pop[[S0]]{{$}}
+; CHECK-NEXT: i32.const $push[[S1:[0-9]+]]=, 37{{$}}
+; CHECK-NEXT: set_local [[L1:[0-9]+]], $pop[[S1]]{{$}}
+; CHECK:      foo [[L2:[0-9]+]], 1, [[L0]], [[L1]]{{$}}
+; CHECK:      get_local $push{{[0-9]+}}=, [[L2]]{{$}}
+define hidden i32 @r_constraint(i32 %a, i32 %y) {
+entry:
+  %z = bitcast i32 0 to i32
+  %t0 = tail call i32 asm "foo $0, $1, $2, $3", "=r,r,r,r"(i32 %y, i32 %z, i32 37) #0, !srcloc !0
+  ret i32 %t0
+}
+
 attributes #0 = { nounwind }
 
 !0 = !{i32 47}
-- 
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