From 954ec09aed4f2be04bb5f4e10dbb4ea8bd19ef9a Mon Sep 17 00:00:00 2001
From: Jennifer Yu <jennifer.yu@intel.com>
Date: Thu, 30 May 2019 01:05:46 +0000
Subject: clang support gnu asm goto. Syntax:   asm [volatile] goto (
 AssemblerTemplate                       :                       :
 InputOperands                       : Clobbers                       :
 GotoLabels)

https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html

New llvm IR is "callbr" for inline asm goto instead "call" for inline asm
For:
asm goto("testl %0, %0; jne %l1;" :: "r"(cond)::label_true, loop);
IR:
callbr void asm sideeffect "testl $0, $0; jne ${1:l};", "r,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %0, i8* blockaddress(@foo, %label_true), i8* blockaddress(@foo, %loop)) #1
          to label %asm.fallthrough [label %label_true, label %loop], !srcloc !3

asm.fallthrough:

Compiler need to generate:
1> a dummy constarint 'X' for each label.
2> an unique fallthrough label for each asm goto stmt " asm.fallthrough%number".


Diagnostic
1>	duplicate asm operand name are used in output, input and label.
2>	goto out of scope.

llvm-svn: 362045
---
 clang/test/CodeGen/asm.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'clang/test/CodeGen/asm.c')

diff --git a/clang/test/CodeGen/asm.c b/clang/test/CodeGen/asm.c
index 038d346e999..7de79639bfd 100644
--- a/clang/test/CodeGen/asm.c
+++ b/clang/test/CodeGen/asm.c
@@ -262,3 +262,15 @@ void t31(int len) {
   // CHECK: @t31
   // CHECK: call void asm sideeffect "", "=*%rm,=*rm,0,1,~{dirflag},~{fpsr},~{flags}"
 }
+
+// CHECK: @t32
+int t32(int cond)
+{
+  asm goto("testl %0, %0; jne %l1;" :: "r"(cond)::label_true, loop);
+  // CHECK: callbr void asm sideeffect "testl $0, $0; jne ${1:l};", "r,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %0, i8* blockaddress(@t32, %label_true), i8* blockaddress(@t32, %loop)) #1
+  return 0;
+loop:
+  return 0;
+label_true:
+  return 1;
+}
-- 
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