Fix shift overflow bug that would occur when a field was a full 32-bits

in tblgen.  This is PR2827, thanks to Waldemar Knorr for tracking this
down.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57124 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/utils/TableGen/CodeEmitterGen.cpp b/utils/TableGen/CodeEmitterGen.cpp
index 62df686ea28b5e37d1cf9b7fd7277ee083d349ac..ae4a6aa445b1ca0f80316202f0a61b2f0751f8e5 100644 (file)
--- a/utils/TableGen/CodeEmitterGen.cpp
+++ b/utils/TableGen/CodeEmitterGen.cpp
@@ -191,7 +191,7 @@ void CodeEmitterGen::run(std::ostream &o) {
               gotOp = true;
             }
             
-            unsigned opMask = (1 << N) - 1;
+            unsigned opMask = ~0U >> (32-N);
             int opShift = beginVarBit - N + 1;
             opMask <<= opShift;
             opShift = beginInstBit - beginVarBit;