llvm-mc: Move AsmExpr into MC lib (as MCExpr).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80567 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCExpr.cpp b/lib/MC/MCExpr.cpp
new file mode 100644
index 0000000..91ef7e7
--- /dev/null
+++ b/lib/MC/MCExpr.cpp
@@ -0,0 +1,162 @@
+//===- MCExpr.cpp - Assembly Level Expression Implementation --------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCValue.h"
+using namespace llvm;
+
+MCExpr::~MCExpr() {
+}
+
+bool MCExpr::EvaluateAsAbsolute(MCContext &Ctx, int64_t &Res) const {
+ MCValue Value;
+
+ if (!EvaluateAsRelocatable(Ctx, Value) || !Value.isAbsolute())
+ return false;
+
+ Res = Value.getConstant();
+ return true;
+}
+
+static bool EvaluateSymbolicAdd(const MCValue &LHS, const MCSymbol *RHS_A,
+ const MCSymbol *RHS_B, int64_t RHS_Cst,
+ MCValue &Res) {
+ // We can't add or subtract two symbols.
+ if ((LHS.getSymA() && RHS_A) ||
+ (LHS.getSymB() && RHS_B))
+ return false;
+
+ const MCSymbol *A = LHS.getSymA() ? LHS.getSymA() : RHS_A;
+ const MCSymbol *B = LHS.getSymB() ? LHS.getSymB() : RHS_B;
+ if (B) {
+ // If we have a negated symbol, then we must have also have a non-negated
+ // symbol in order to encode the expression. We can do this check later to
+ // permit expressions which eventually fold to a representable form -- such
+ // as (a + (0 - b)) -- if necessary.
+ if (!A)
+ return false;
+ }
+ Res = MCValue::get(A, B, LHS.getConstant() + RHS_Cst);
+ return true;
+}
+
+bool MCExpr::EvaluateAsRelocatable(MCContext &Ctx, MCValue &Res) const {
+ switch (getKind()) {
+ default:
+ assert(0 && "Invalid assembly expression kind!");
+
+ case Constant:
+ Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
+ return true;
+
+ case SymbolRef: {
+ MCSymbol *Sym = cast<MCSymbolRefExpr>(this)->getSymbol();
+ if (const MCValue *Value = Ctx.GetSymbolValue(Sym))
+ Res = *Value;
+ else
+ Res = MCValue::get(Sym, 0, 0);
+ return true;
+ }
+
+ case Unary: {
+ const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
+ MCValue Value;
+
+ if (!AUE->getSubExpr()->EvaluateAsRelocatable(Ctx, Value))
+ return false;
+
+ switch (AUE->getOpcode()) {
+ case MCUnaryExpr::LNot:
+ if (!Value.isAbsolute())
+ return false;
+ Res = MCValue::get(!Value.getConstant());
+ break;
+ case MCUnaryExpr::Minus:
+ /// -(a - b + const) ==> (b - a - const)
+ if (Value.getSymA() && !Value.getSymB())
+ return false;
+ Res = MCValue::get(Value.getSymB(), Value.getSymA(),
+ -Value.getConstant());
+ break;
+ case MCUnaryExpr::Not:
+ if (!Value.isAbsolute())
+ return false;
+ Res = MCValue::get(~Value.getConstant());
+ break;
+ case MCUnaryExpr::Plus:
+ Res = Value;
+ break;
+ }
+
+ return true;
+ }
+
+ case Binary: {
+ const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
+ MCValue LHSValue, RHSValue;
+
+ if (!ABE->getLHS()->EvaluateAsRelocatable(Ctx, LHSValue) ||
+ !ABE->getRHS()->EvaluateAsRelocatable(Ctx, RHSValue))
+ return false;
+
+ // We only support a few operations on non-constant expressions, handle
+ // those first.
+ if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
+ switch (ABE->getOpcode()) {
+ default:
+ return false;
+ case MCBinaryExpr::Sub:
+ // Negate RHS and add.
+ return EvaluateSymbolicAdd(LHSValue,
+ RHSValue.getSymB(), RHSValue.getSymA(),
+ -RHSValue.getConstant(),
+ Res);
+
+ case MCBinaryExpr::Add:
+ return EvaluateSymbolicAdd(LHSValue,
+ RHSValue.getSymA(), RHSValue.getSymB(),
+ RHSValue.getConstant(),
+ Res);
+ }
+ }
+
+ // 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).
+ int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
+ int64_t Result = 0;
+ switch (ABE->getOpcode()) {
+ case MCBinaryExpr::Add: Result = LHS + RHS; break;
+ case MCBinaryExpr::And: Result = LHS & RHS; break;
+ case MCBinaryExpr::Div: Result = LHS / RHS; break;
+ case MCBinaryExpr::EQ: Result = LHS == RHS; break;
+ case MCBinaryExpr::GT: Result = LHS > RHS; break;
+ case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
+ case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
+ case MCBinaryExpr::LOr: Result = LHS || RHS; break;
+ case MCBinaryExpr::LT: Result = LHS < RHS; break;
+ case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
+ case MCBinaryExpr::Mod: Result = LHS % RHS; break;
+ case MCBinaryExpr::Mul: Result = LHS * RHS; break;
+ case MCBinaryExpr::NE: Result = LHS != RHS; break;
+ case MCBinaryExpr::Or: Result = LHS | RHS; break;
+ case MCBinaryExpr::Shl: Result = LHS << RHS; break;
+ case MCBinaryExpr::Shr: Result = LHS >> RHS; break;
+ case MCBinaryExpr::Sub: Result = LHS - RHS; break;
+ case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
+ }
+
+ Res = MCValue::get(Result);
+ return true;
+ }
+ }
+}
+