[llvm] r251818 - ELF can handle some relocations of the form -sym + constant.
Rafael Espindola via llvm-commits
llvm-commits at lists.llvm.org
Mon Nov 2 11:13:59 PST 2015
Author: rafael
Date: Mon Nov 2 13:13:59 2015
New Revision: 251818
URL: http://llvm.org/viewvc/llvm-project?rev=251818&view=rev
Log:
ELF can handle some relocations of the form -sym + constant.
Remove code that was assuming that this would never work.
Thanks to Colin LeMahie for finding and diagnosing the bug.
Modified:
llvm/trunk/include/llvm/MC/MCValue.h
llvm/trunk/lib/MC/MCExpr.cpp
llvm/trunk/test/MC/ELF/relocation-pc.s
Modified: llvm/trunk/include/llvm/MC/MCValue.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCValue.h?rev=251818&r1=251817&r2=251818&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCValue.h (original)
+++ llvm/trunk/include/llvm/MC/MCValue.h Mon Nov 2 13:13:59 2015
@@ -35,10 +35,6 @@ class raw_ostream;
/// relocation modifiers apply to the closest symbol or the whole
/// expression.
///
-/// In the general form, SymbolB can only be defined if SymbolA is, and both
-/// 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
/// it to live in unions etc.
class MCValue {
@@ -67,7 +63,6 @@ public:
const MCSymbolRefExpr *SymB = nullptr,
int64_t Val = 0, uint32_t RefKind = 0) {
MCValue R;
- assert((!SymB || SymA) && "Invalid relocatable MCValue!");
R.Cst = Val;
R.SymA = SymA;
R.SymB = SymB;
Modified: llvm/trunk/lib/MC/MCExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCExpr.cpp?rev=251818&r1=251817&r2=251818&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCExpr.cpp (original)
+++ llvm/trunk/lib/MC/MCExpr.cpp Mon Nov 2 13:13:59 2015
@@ -585,11 +585,6 @@ EvaluateSymbolicAdd(const MCAssembler *A
const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
- // If we have a negated symbol, then we must have also have a non-negated
- // symbol in order to encode the expression.
- if (B && !A)
- return false;
-
Res = MCValue::get(A, B, Result_Cst);
return true;
}
Modified: llvm/trunk/test/MC/ELF/relocation-pc.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ELF/relocation-pc.s?rev=251818&r1=251817&r2=251818&view=diff
==============================================================================
--- llvm/trunk/test/MC/ELF/relocation-pc.s (original)
+++ llvm/trunk/test/MC/ELF/relocation-pc.s Mon Nov 2 13:13:59 2015
@@ -4,6 +4,7 @@
loope 0 # R_X86_64_PC8
jmp -256 # R_X86_64_PC32
+ .word 0x42 - . # R_X86_64_PC16
// CHECK: Section {
// CHECK: Index:
@@ -13,7 +14,7 @@
// CHECK-NEXT: ]
// CHECK-NEXT: Address: 0x0
// CHECK-NEXT: Offset:
-// CHECK-NEXT: Size: 48
+// CHECK-NEXT: Size:
// CHECK-NEXT: Link:
// CHECK-NEXT: Info:
// CHECK-NEXT: AddressAlignment: 8
@@ -21,5 +22,6 @@
// CHECK-NEXT: Relocations [
// CHECK-NEXT: 0x1 R_X86_64_PC8 - 0xFFFFFFFFFFFFFFFF
// CHECK-NEXT: 0x3 R_X86_64_PC32 - 0xFFFFFFFFFFFFFEFC
+// CHECK-NEXT: 0x7 R_X86_64_PC16 - 0x42
// CHECK-NEXT: ]
// CHECK-NEXT: }
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