The return value of a comparison operator is -1 if true and 0 if false

[void]

Summary

Correct compatibility with the GNU Assembler's handling of the comparison operators. 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

[void]

Add fix for MIPS test.

[niravd]

lib/MC/MCExpr.cpp

805

The docs say Land and LOr must be 0 or 1.

test/MC/Mips/memory-offsets.s

21 ↗

(On Diff #146504)

This should be reverted given above.

[void]

lib/MC/MCExpr.cpp

805

Ah! Good catch. Done.

[void]

Fix logical operators. They return 1 or 0, not -1 or 0.

[niravd]

LGTM.

lib/MC/MCExpr.cpp

     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;
   }
 

     // 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;

     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;
   }
   }

test/MC/AsmParser/altmacro_string.s

 # Test #3:
 # The altmacro cannot affect the regular less/greater behavior.
 
-# CHECK: addl $1, %eax
+# CHECK: addl $-1, %eax
 # CHECK: addl $0, %eax
 
 .macro fun3 arg1 arg2

test/MC/AsmParser/directive_space.s

         .space 2, 3
 
 # CHECK: TEST2:
+# CHECK: .space 1,3
+TEST2:  
+        .space -(2 > 0), 3
+
+# CHECK: TEST3:
 # CHECK: .space 1
-TEST2:
+TEST3:
         .skip 1
 
-# CHECK: TEST3
+# CHECK: TEST4
 # CHECK: .space TEST0-TEST1
-TEST3:
-        .space TEST0 - TEST1
+TEST4:
+        .skip TEST0 - TEST1
+
+# CHECK: TEST5
+# CHECK: .space -((TEST0-TEST1)>0)
+TEST5:
+        .skip -((TEST0 - TEST1) > 0)

test/MC/AsmParser/exprs.s

         check_expr 1 & 3, 1
         check_expr 4 / 2, 2
         check_expr 4 / -2, -2
-        check_expr 1 == 1, 1
+        check_expr 1 == 1, -1
         check_expr 1 == 0, 0
-        check_expr 1 > 0, 1
-        check_expr 1 >= 1, 1
-        check_expr 1 < 2, 1
-        check_expr 1 <= 1, 1
+        check_expr 1 > 0, -1
+        check_expr 1 >= 1, -1
+        check_expr 1 < 2, -1
+        check_expr 1 <= 1, -1
         check_expr 4 % 3, 1
         check_expr 2 * 2, 4
         check_expr 2 != 2, 0

         check_expr 1 || 2, 1
         check_expr 0 || 1, 1
         check_expr 0 || 0, 0
-        check_expr 1 + 2 < 3 + 4, 1
+        check_expr 1 + 2 < 3 + 4, -1
         check_expr 1 << 8 - 1, 128
         check_expr 3 * 9 - 2 * 9 + 1, 10