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llvm-mc: Symbols in a relocatable expression of the (a - b + cst) form are

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allowed to be undefined when the expression is seen, we cannot enforce the
same-section requirement until the entire assembly file has been seen.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74565 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar
2009-06-30 22:49:27 +00:00
parent 20c568f366
commit 374d8bddac
3 changed files with 14 additions and 9 deletions
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7
include/llvm/MC/MCValue.h
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@@ -26,7 +26,8 @@ class MCSymbol;
/// relocations of this general form, but we need to represent this anyway. /// relocations of this general form, but we need to represent this anyway.
/// ///
/// In the general form, SymbolB can only be defined if SymbolA is, and both /// In the general form, SymbolB can only be defined if SymbolA is, and both
/// must be in the same (non-external) section. /// must be in the same (non-external) section. The latter constraint is not
/// enforced, since a symbol's section may not be known at construction.
/// ///
/// Note that this class must remain a simple POD value class, because we need /// Note that this class must remain a simple POD value class, because we need
/// it to live in unions etc. /// it to live in unions etc.
@@ -52,9 +53,7 @@ public:
static MCValue get(MCSymbol *SymA, MCSymbol *SymB = 0, int64_t Val = 0) { static MCValue get(MCSymbol *SymA, MCSymbol *SymB = 0, int64_t Val = 0) {
MCValue R; MCValue R;
assert((!SymB || (SymA && SymA->getSection() && assert((!SymB || SymA) && "Invalid relocatable MCValue!");
SymA->getSection() == SymB->getSection())) &&
"Invalid relocatable MCValue!");
R.Cst = Val; R.Cst = Val;
R.SymA = SymA; R.SymA = SymA;
R.SymB = SymB; R.SymB = SymB;

7
test/MC/AsmParser/exprs.s
View File

@@ -52,4 +52,11 @@ k:
i = (j + 10) - (k + 2) i = (j + 10) - (k + 2)
.long i .long i
l = m - n + 4
.text
m:
n:
nop

9
tools/llvm-mc/AsmExpr.cpp
View File

@@ -37,12 +37,11 @@ static bool EvaluateSymbolicAdd(const MCValue &LHS, MCSymbol *RHS_A,
MCSymbol *A = LHS.getSymA() ? LHS.getSymA() : RHS_A; MCSymbol *A = LHS.getSymA() ? LHS.getSymA() : RHS_A;
MCSymbol *B = LHS.getSymB() ? LHS.getSymB() : RHS_B; MCSymbol *B = LHS.getSymB() ? LHS.getSymB() : RHS_B;
if (B) { if (B) {
// If we have a negated symbol, then we must have also have a // If we have a negated symbol, then we must have also have a non-negated
// non-negated symbol, and both symbols must be in the same // symbol in order to encode the expression. We can do this check later to
// non-external section. We can do this check later to permit // permit expressions which eventually fold to a representable form -- such
// expressions which eventually fold to a representable form -- such
// as (a + (0 - b)) -- if necessary. // as (a + (0 - b)) -- if necessary.
if (!A || !A->getSection() || A->getSection() != B->getSection()) if (!A)
return false; return false;
} }
Res = MCValue::get(A, B, LHS.getConstant() + RHS_Cst); Res = MCValue::get(A, B, LHS.getConstant() + RHS_Cst);