Document that MCExpr::Mod is actually remainder.
Document that MCExpr::Div, Mod, and the comparison operators are all
signed operators.
Document that the comparison operators' results are target-dependent.
Document that the behavior of shr is target-dependent.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95619 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/MC/MCExpr.h b/include/llvm/MC/MCExpr.h
index 04eeb66..afc90d9 100644
--- a/include/llvm/MC/MCExpr.h
+++ b/include/llvm/MC/MCExpr.h
@@ -202,20 +202,24 @@
enum Opcode {
Add, ///< Addition.
And, ///< Bitwise and.
- Div, ///< Division.
+ Div, ///< Signed division.
EQ, ///< Equality comparison.
- GT, ///< Greater than comparison.
- GTE, ///< Greater than or equal comparison.
+ GT, ///< Signed greater than comparison (result is either 0 or some
+ ///< target-specific non-zero value)
+ GTE, ///< Signed greater than or equal comparison (result is either 0 or
+ ///< some target-specific non-zero value).
LAnd, ///< Logical and.
LOr, ///< Logical or.
- LT, ///< Less than comparison.
- LTE, ///< Less than or equal comparison.
- Mod, ///< Modulus.
+ LT, ///< Signed less than comparison (result is either 0 or
+ ///< some target-specific non-zero value).
+ LTE, ///< Signed less than or equal comparison (result is either 0 or
+ ///< some target-specific non-zero value).
+ Mod, ///< Signed remainder.
Mul, ///< Multiplication.
NE, ///< Inequality comparison.
Or, ///< Bitwise or.
- Shl, ///< Bitwise shift left.
- Shr, ///< Bitwise shift right.
+ Shl, ///< Shift left.
+ Shr, ///< Shift right (arithmetic or logical, depending on target)
Sub, ///< Subtraction.
Xor ///< Bitwise exclusive or.
};
diff --git a/lib/MC/MCExpr.cpp b/lib/MC/MCExpr.cpp
index afdaa00..e419043 100644
--- a/lib/MC/MCExpr.cpp
+++ b/lib/MC/MCExpr.cpp
@@ -252,8 +252,8 @@
}
// FIXME: We need target hooks for the evaluation. It may be limited in
- // width, and gas defines the result of comparisons differently from Apple
- // as (the result is sign extended).
+ // width, and gas defines the result of comparisons and right shifts
+ // differently from Apple as.
int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
int64_t Result = 0;
switch (ABE->getOpcode()) {