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Fix PR c++/64697 at -O1 or above

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The BFD fix eliminates the link failure and working code is generated at
-O0, but _not_ when optimization is enabled because the optimizer changes:

        movq    .refptr._ZTH1s(%rip), %rax
        testq   %rax, %rax
        je      .L2
        call    _ZTH1s

into:

        leaq    _ZTH1s(%rip), %rax
        testq   %rax, %rax
        je      .L2
        call    _ZTH1s

and the leaq now also gets the relocation overflow.  So the fix is to
teach legitimate_pic_address_disp_p to reject the transformation when
the symbol is an external weak function, which yields:

        cmpq    $0, .refptr._ZTH1s(%rip)
        je      .L2
        call    _ZTH1s

and the cmpq keeps a relocation that does not overflow.

gcc/
	PR c++/64697
	* config/i386/i386.c (legitimate_pic_address_disp_p): For PE-COFF do
	not return true for external weak function symbols in medium model.
This commit is contained in:
Eric Botcazou 2021-10-01 10:49:34 +02:00
parent e705b8533a
commit 021ad8e5cf
1 changed files with 8 additions and 13 deletions
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21
gcc/config/i386/i386.c
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@ -10708,24 +10708,19 @@ legitimate_pic_address_disp_p (rtx disp)
if (is_imported_p (op0))
return true;
if (SYMBOL_REF_FAR_ADDR_P (op0)
|| !SYMBOL_REF_LOCAL_P (op0))
if (SYMBOL_REF_FAR_ADDR_P (op0) || !SYMBOL_REF_LOCAL_P (op0))
break;
/* Function-symbols need to be resolved only for
large-model.
For the small-model we don't need to resolve anything
here. */
/* Non-external-weak function symbols need to be resolved only
for the large model. Non-external symbols don't need to be
resolved for large and medium models. For the small model,
we don't need to resolve anything here. */
if ((ix86_cmodel != CM_LARGE_PIC
&& SYMBOL_REF_FUNCTION_P (op0))
&& SYMBOL_REF_FUNCTION_P (op0)
&& !(SYMBOL_REF_EXTERNAL_P (op0) && SYMBOL_REF_WEAK (op0)))
|| !SYMBOL_REF_EXTERNAL_P (op0)
|| ix86_cmodel == CM_SMALL_PIC)
return true;
/* Non-external symbols don't need to be resolved for
large, and medium-model. */
if ((ix86_cmodel == CM_LARGE_PIC
|| ix86_cmodel == CM_MEDIUM_PIC)
&& !SYMBOL_REF_EXTERNAL_P (op0))
return true;
}
else if (!SYMBOL_REF_FAR_ADDR_P (op0)
&& (SYMBOL_REF_LOCAL_P (op0)