From: Duncan P. N. Exon Smith <dexonsmith@apple.com>
Date: Mon, 16 Dec 2013 03:20:06 +0000 (+0000)
Subject: Stop crashing on empty asm input constraints
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ff1554738da8fed4bbb53fecab7f369d56a0cd66;p=clang

Stop crashing on empty asm input constraints

An empty string for an ASM input constraint is invalid, and will crash
during clang CodeGen.  Change TargetInfo::validateInputConstraint to
reject an empty string.

<rdar://problem/15552191>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@197362 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Basic/TargetInfo.cpp b/lib/Basic/TargetInfo.cpp
index 5aa84afc4d..d0ed6e6b16 100644
--- a/lib/Basic/TargetInfo.cpp
+++ b/lib/Basic/TargetInfo.cpp
@@ -482,6 +482,9 @@ bool TargetInfo::validateInputConstraint(ConstraintInfo *OutputConstraints,
                                          ConstraintInfo &Info) const {
   const char *Name = Info.ConstraintStr.c_str();
 
+  if (!*Name)
+    return false;
+
   while (*Name) {
     switch (*Name) {
     default:
diff --git a/test/Sema/asm.c b/test/Sema/asm.c
index c81f16a387..1559b228c8 100644
--- a/test/Sema/asm.c
+++ b/test/Sema/asm.c
@@ -13,6 +13,9 @@ void f() {
   asm ("foo\n" : "=a" (i) : "[" (i)); // expected-error {{invalid input constraint '[' in asm}}
   asm ("foo\n" : "=a" (i) : "[foo" (i)); // expected-error {{invalid input constraint '[foo' in asm}}
   asm ("foo\n" : "=a" (i) : "[symbolic_name]" (i)); // expected-error {{invalid input constraint '[symbolic_name]' in asm}}
+
+  asm ("foo\n" : : "" (i)); // expected-error {{invalid input constraint '' in asm}}
+  asm ("foo\n" : "=a" (i) : "" (i)); // expected-error {{invalid input constraint '' in asm}}
 }
 
 void clobbers() {