From: Olivier Goffart <ogoffart@woboq.com>
Date: Sun, 17 Aug 2014 13:19:48 +0000 (+0000)
Subject: Fix assertion on asm register that are "%"
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b7c04bc25674de63a710d380f5145a6446e4b8ae;p=clang

Fix assertion on asm register that are "%"

Name might be empty again after we removed the '%' prefix
and Name[0] would assert.

Found on code like
register int foo asm("%" MACRO);
where MACRO was supposed to be defined in a header file that was not found.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215834 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Basic/TargetInfo.cpp b/lib/Basic/TargetInfo.cpp
index aecf13b008..a35298067b 100644
--- a/lib/Basic/TargetInfo.cpp
+++ b/lib/Basic/TargetInfo.cpp
@@ -338,6 +338,8 @@ bool TargetInfo::isValidGCCRegisterName(StringRef Name) const {
 
   // Get rid of any register prefix.
   Name = removeGCCRegisterPrefix(Name);
+  if (Name.empty())
+      return false;
 
   getGCCRegNames(Names, NumNames);
 
diff --git a/test/Sema/asm.c b/test/Sema/asm.c
index 89c8c574eb..13ae25f265 100644
--- a/test/Sema/asm.c
+++ b/test/Sema/asm.c
@@ -107,6 +107,7 @@ void test10(void){
 
   register int r asm ("cx");
   register int rr asm ("rr_asm"); // expected-error{{unknown register name 'rr_asm' in asm}}
+  register int rrr asm ("%"); // expected-error{{unknown register name '%' in asm}}
 }
 
 // This is just an assert because of the boolean conversion.