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/lib/Parse/ParseStmtAsm.cpp | 68 ++++++++++++++++++++++++++++++++++------
 1 file changed, 58 insertions(+), 10 deletions(-)

(limited to 'clang/lib/Parse/ParseStmtAsm.cpp')

diff --git a/clang/lib/Parse/ParseStmtAsm.cpp b/clang/lib/Parse/ParseStmtAsm.cpp
index c63808a472b..75f3ac396e1 100644
--- a/clang/lib/Parse/ParseStmtAsm.cpp
+++ b/clang/lib/Parse/ParseStmtAsm.cpp
@@ -710,12 +710,12 @@ StmtResult Parser::ParseAsmStatement(bool &msAsm) {
 
   // Remember if this was a volatile asm.
   bool isVolatile = DS.getTypeQualifiers() & DeclSpec::TQ_volatile;
+  // Remember if this was a goto asm.
+  bool isGotoAsm = false;
 
-  // TODO: support "asm goto" constructs (PR#9295).
   if (Tok.is(tok::kw_goto)) {
-    Diag(Tok, diag::err_asm_goto_not_supported_yet);
-    SkipUntil(tok::r_paren, StopAtSemi);
-    return StmtError();
+    isGotoAsm = true;
+    ConsumeToken();
   }
 
   if (Tok.isNot(tok::l_paren)) {
@@ -753,7 +753,8 @@ StmtResult Parser::ParseAsmStatement(bool &msAsm) {
     return Actions.ActOnGCCAsmStmt(AsmLoc, /*isSimple*/ true, isVolatile,
                                    /*NumOutputs*/ 0, /*NumInputs*/ 0, nullptr,
                                    Constraints, Exprs, AsmString.get(),
-                                   Clobbers, T.getCloseLocation());
+                                   Clobbers, /*NumLabels*/ 0,
+                                   T.getCloseLocation());
   }
 
   // Parse Outputs, if present.
@@ -763,6 +764,12 @@ StmtResult Parser::ParseAsmStatement(bool &msAsm) {
     AteExtraColon = Tok.is(tok::coloncolon);
     ConsumeToken();
 
+    if (!AteExtraColon && isGotoAsm && Tok.isNot(tok::colon)) {
+      Diag(Tok, diag::err_asm_goto_cannot_have_output);
+      SkipUntil(tok::r_paren, StopAtSemi);
+      return StmtError();
+    }
+
     if (!AteExtraColon && ParseAsmOperandsOpt(Names, Constraints, Exprs))
       return StmtError();
   }
@@ -789,12 +796,15 @@ StmtResult Parser::ParseAsmStatement(bool &msAsm) {
   unsigned NumInputs = Names.size() - NumOutputs;
 
   // Parse the clobbers, if present.
-  if (AteExtraColon || Tok.is(tok::colon)) {
-    if (!AteExtraColon)
+  if (AteExtraColon || Tok.is(tok::colon) || Tok.is(tok::coloncolon)) {
+    if (AteExtraColon)
+      AteExtraColon = false;
+    else {
+      AteExtraColon = Tok.is(tok::coloncolon);
       ConsumeToken();
-
+    }
     // Parse the asm-string list for clobbers if present.
-    if (Tok.isNot(tok::r_paren)) {
+    if (!AteExtraColon && isTokenStringLiteral()) {
       while (1) {
         ExprResult Clobber(ParseAsmStringLiteral());
 
@@ -808,11 +818,49 @@ StmtResult Parser::ParseAsmStatement(bool &msAsm) {
       }
     }
   }
+  if (!isGotoAsm && (Tok.isNot(tok::r_paren) || AteExtraColon)) {
+    Diag(Tok, diag::err_expected) << tok::r_paren;
+    SkipUntil(tok::r_paren, StopAtSemi);
+    return StmtError();
+  }
+
+  // Parse the goto label, if present.
+  unsigned NumLabels = 0;
+  if (AteExtraColon || Tok.is(tok::colon)) {
+    if (!AteExtraColon)
+      ConsumeToken();
 
+    while (true) {
+      if (Tok.isNot(tok::identifier)) {
+        Diag(Tok, diag::err_expected) << tok::identifier;
+        SkipUntil(tok::r_paren, StopAtSemi);
+        return StmtError();
+      }
+      LabelDecl *LD = Actions.LookupOrCreateLabel(Tok.getIdentifierInfo(),
+                                                  Tok.getLocation());
+      Names.push_back(Tok.getIdentifierInfo());
+      if (!LD) {
+        SkipUntil(tok::r_paren, StopAtSemi);
+        return StmtError();
+      }
+      ExprResult Res =
+          Actions.ActOnAddrLabel(Tok.getLocation(), Tok.getLocation(), LD);
+      Exprs.push_back(Res.get());
+      NumLabels++;
+      ConsumeToken();
+      if (!TryConsumeToken(tok::comma))
+        break;
+    }
+  } else if (isGotoAsm) {
+    Diag(Tok, diag::err_expected) << tok::colon;
+    SkipUntil(tok::r_paren, StopAtSemi);
+    return StmtError();
+  }
   T.consumeClose();
   return Actions.ActOnGCCAsmStmt(
       AsmLoc, false, isVolatile, NumOutputs, NumInputs, Names.data(),
-      Constraints, Exprs, AsmString.get(), Clobbers, T.getCloseLocation());
+      Constraints, Exprs, AsmString.get(), Clobbers, NumLabels,
+      T.getCloseLocation());
 }
 
 /// ParseAsmOperands - Parse the asm-operands production as used by
-- 
cgit v1.2.3