[inlineasm] Fix crash when number of matched input constraint operands overflows signed char

In a case when number of output constraint operands that has matched input operands
doesn't fit to signed char, TargetLowering::ParseConstraints() can try to access
ConstraintOperands (that is std::vector) with negative index.

Reviewers: rampitec, arsenm

Differential Review: https://reviews.llvm.org/D39125

llvm-svn: 316574

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/IR/InlineAsm.cpp b/llvm/lib/IR/InlineAsm.cpp
index ad22efdf0ef..8667d7aab58 100644
--- a/llvm/lib/IR/InlineAsm.cpp
+++ b/llvm/lib/IR/InlineAsm.cpp
@@ -163,6 +163,7 @@ bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
           return true;
         // Note that operand #n has a matching input.
         scInfo.MatchingInput = ConstraintsSoFar.size();
+        assert(scInfo.MatchingInput >= 0);
       } else {
         if (ConstraintsSoFar[N].hasMatchingInput() &&
             (size_t)ConstraintsSoFar[N].MatchingInput !=
@@ -170,6 +171,7 @@ bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
           return true;
         // Note that operand #n has a matching input.
         ConstraintsSoFar[N].MatchingInput = ConstraintsSoFar.size();
+        assert(ConstraintsSoFar[N].MatchingInput >= 0);
         }
     } else if (*I == '|') {
       multipleAlternativeIndex++;