From: Eric Botcazou <ebotcazou@adacore.com>
Date: Fri, 1 Oct 2021 08:49:34 +0000 (+0200)
Subject: Fix PR c++/64697 at -O1 or above
X-Git-Tag: basepoints/gcc-13~4277
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=021ad8e5cf9ab66e1a0a41dce3a54586facb86e0;p=thirdparty%2Fgcc.git

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

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.
---

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 5aeb44c9005f..a566d84a61e5 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -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)