`.symver foo, foo@ver` creates the MCSymbolELF `foo@ver` whose almost all
attributes (including st_size) should inherit from `foo` (GNU as behavior).
a041ef1bd8905f0d58e301c6830b183002ff1847 added st_size propagation which works
for many cases but fails for the following one:
```
.set __GLIBC_2_12_sys_errlist, _sys_errlist_internal
.type __GLIBC_2_12_sys_errlist,@object
.size __GLIBC_2_12_sys_errlist, 1080
.symver __GLIBC_2_12_sys_errlist, sys_errlist@GLIBC_2.12
...
_sys_errlist_internal:
.size _sys_errlist_internal, 1072
```
`sys_errlist@GLIBC_2.12`'s st_size is 1072 (incorrect), which does not match
`__GLIBC_2_12_sys_errlist`'s st_size: 1080.
The problem is that `Base` is (the final) `_sys_errlist_internal` while we want
to respect (the intermediate) `__GLIBC_2_12_sys_errlist`'s st_size.
Fix this by following the MCSymbolRefExpr assignment chain and finding
the closest non-null `getSize()`, which covers most needs. Notably MCBinaryExpr
is not handled, but it is rare enough to matter.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D123283
uint64_t Size = 0;
const MCExpr *ESize = MSD.Symbol->getSize();
- if (!ESize && Base)
+ if (!ESize && Base) {
+ // For expressions like .set y, x+1, if y's size is unset, inherit from x.
ESize = Base->getSize();
+ // For `.size x, 2; y = x; .size y, 1; z = y; z1 = z; .symver y, y@v1`, z,
+ // z1, and y@v1's st_size equals y's. However, `Base` is `x` which will give
+ // us 2. Follow the MCSymbolRefExpr assignment chain, which covers most
+ // needs. MCBinaryExpr is not handled.
+ const MCSymbolELF *Sym = &Symbol;
+ while (Sym->isVariable()) {
+ if (auto *Expr =
+ dyn_cast<MCSymbolRefExpr>(Sym->getVariableValue(false))) {
+ Sym = cast<MCSymbolELF>(&Expr->getSymbol());
+ if (!Sym->getSize())
+ continue;
+ ESize = Sym->getSize();
+ }
+ break;
+ }
+ }
+
if (ESize) {
int64_t Res;
if (!ESize->evaluateKnownAbsolute(Res, Layout))
# CHECK-NEXT: 000000000000000d 42 OBJECT GLOBAL DEFAULT [[#A]] d1
# CHECK-NEXT: 000000000000000d 42 OBJECT GLOBAL DEFAULT [[#A]] d2
# CHECK-NEXT: 0000000000000001 41 OBJECT GLOBAL DEFAULT [[#A]] e
-# CHECK-NEXT: 0000000000000001 42 OBJECT GLOBAL DEFAULT [[#A]] e1
-# CHECK-NEXT: 0000000000000001 42 OBJECT GLOBAL DEFAULT [[#A]] e2
+# CHECK-NEXT: 0000000000000001 41 OBJECT GLOBAL DEFAULT [[#A]] e1
+# CHECK-NEXT: 0000000000000001 41 OBJECT GLOBAL DEFAULT [[#A]] e2
# CHECK-NEXT: 0000000000000002 42 OBJECT GLOBAL DEFAULT [[#A]] e3
# CHECK-NEXT: 0000000000000005 0 NOTYPE GLOBAL DEFAULT [[#A]] test2_a
# CHECK-NEXT: 0000000000000005 0 NOTYPE GLOBAL DEFAULT [[#A]] test2_b
# CHECK-NEXT: 0000000000000009 0 NOTYPE GLOBAL DEFAULT [[#A]] test2_c
# CHECK-NEXT: 0000000000000009 0 NOTYPE GLOBAL DEFAULT [[#A]] test2_d
# CHECK-NEXT: 0000000000000004 0 NOTYPE GLOBAL DEFAULT ABS test2_e
-# CHECK-NEXT: 0000000000000001 42 OBJECT GLOBAL DEFAULT [[#A]] e@v1
+# CHECK-NEXT: 0000000000000001 41 OBJECT GLOBAL DEFAULT [[#A]] e@v1
.data
e = a + (1 - 1)
.size e, 41
-## FIXME These st_size fields inherit from e instead of a.
+## These st_size fields inherit from e instead of a.
+## TODO e3's st_size should inherit from e.
.set e1, e
.set e2, e1
e3 = e1 + 1