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

3 files changed, 35 insertions, 5 deletions

diff --git a/clang/test/CodeGen/asm-goto.c b/clang/test/CodeGen/asm-goto.c
new file mode 100644
index 00000000000..2c4a1a0c4df
--- /dev/null
+++ b/clang/test/CodeGen/asm-goto.c
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -O0 -emit-llvm  %s -o - | FileCheck %s
+
+int foo(int cond)
+{
+  // CHECK: callbr void asm sideeffect
+  // CHECK: to label %asm.fallthrough [label %label_true, label %loop], !srcloc !2
+  // CHECK: asm.fallthrough:
+  asm volatile goto("testl %0, %0; jne %l1;" :: "r"(cond)::label_true, loop);
+  asm volatile goto("testl %0, %0; jne %l1;" :: "r"(cond)::label_true, loop);
+  // CHECK: callbr void asm sideeffect
+  // CHECK: to label %asm.fallthrough1 [label %label_true, label %loop], !srcloc !3
+  // CHECK: asm.fallthrough1:
+  return 0;
+loop:
+  return 0;
+label_true:
+  return 1;
+}
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;
+}
diff --git a/clang/test/CodeGen/inline-asm-mixed-style.c b/clang/test/CodeGen/inline-asm-mixed-style.c
index 6b830d9fa7a..a9e111cd5dd 100644
--- a/clang/test/CodeGen/inline-asm-mixed-style.c
+++ b/clang/test/CodeGen/inline-asm-mixed-style.c
@@ -1,4 +1,3 @@
-// RUN: %clang_cc1 -triple i386-unknown-unknown -fasm-blocks -fsyntax-only -verify %s -DCHECK_ASM_GOTO
 // RUN: %clang_cc1 -triple i386-unknown-unknown -fasm-blocks -O0 -emit-llvm -S %s -o - | FileCheck %s
 // REQUIRES: x86-registered-target
 
@@ -20,10 +19,11 @@ void f() {
   // CHECK: movl    %ebx, %eax
   // CHECK: movl    %ecx, %edx
 
-#ifdef CHECK_ASM_GOTO
-  __asm volatile goto ("movl %ecx, %edx"); // expected-error {{'asm goto' constructs are not supported yet}}
+  __asm volatile goto ("movl %ecx, %edx");
+  // CHECK: movl    %ecx, %edx
 
   __asm mov eax, ebx
-  __asm goto ("movl %ecx, %edx"); // expected-error {{'asm goto' constructs are not supported yet}}
-#endif
+  __asm goto ("movl %ecx, %edx");
+  // CHECK: movl    %ebx, %eax
+  // CHECK: movl    %ecx, %edx
 }