commit 2a302210d0a34ee6406c88ef727004b826eeca32
author Bill Wendling <isanbard@gmail.com> Mon May 14 05:25:36 2018 +0000
committer Bill Wendling <isanbard@gmail.com> Mon May 14 05:25:36 2018 +0000
tree cbbe5fb5e6ab7c3b3d3aad066adcdf8b3cf4a6e1
parent f633f3eb67dbbb337ae1f929b0f840bd2ba00a67

Correct compatibility with the GNU Assembler's handling of comparison ops

GAS returns -1 for a comparison operator if the result is true and 0 if false.

  https://www.sourceware.org/binutils/docs-2.12/as.info/Infix-Ops.html#Infix%20Ops

llvm-svn: 332215

llvm/lib/MC/MCExpr.cpp

diff --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp
index f9b8889..831c692 100644
--- a/llvm/lib/MC/MCExpr.cpp
+++ b/llvm/lib/MC/MCExpr.cpp
@@ -74,7 +74,10 @@
     case MCUnaryExpr::Not:   OS << '~'; break;
     case MCUnaryExpr::Plus:  OS << '+'; break;
     }
+    bool Binary = UE.getSubExpr()->getKind() == MCExpr::Binary;
+    if (Binary) OS << "(";
     UE.getSubExpr()->print(OS, MAI);
+    if (Binary) OS << ")";
     return;
   }
 
@@ -756,7 +759,8 @@
     // Apple as.
     int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
     int64_t Result = 0;
-    switch (ABE->getOpcode()) {
+    auto Op = ABE->getOpcode();
+    switch (Op) {
     case MCBinaryExpr::AShr: Result = LHS >> RHS; break;
     case MCBinaryExpr::Add:  Result = LHS + RHS; break;
     case MCBinaryExpr::And:  Result = LHS & RHS; break;
@@ -791,7 +795,21 @@
     case MCBinaryExpr::Xor:  Result = LHS ^ RHS; break;
     }
 
-    Res = MCValue::get(Result);
+    switch (Op) {
+    default:
+      Res = MCValue::get(Result);
+      break;
+    case MCBinaryExpr::EQ:
+    case MCBinaryExpr::GT:
+    case MCBinaryExpr::GTE:
+    case MCBinaryExpr::LT:
+    case MCBinaryExpr::LTE:
+    case MCBinaryExpr::NE:
+      // A comparison operator returns a -1 if true and 0 if false.
+      Res = MCValue::get(Result ? -1 : 0);
+      break;
+    }
+
     return true;
   }
   }