Fix access to undefined weak symbols in pic code
When the access to a weak symbol is not a call, the access has to be
able to produce the value 0 at runtime.
We were sometimes producing code sequences where that was not possible
if the code was leaded more than 4g away from 0.
llvm-svn: 310756
diff --git a/llvm/lib/Target/X86/X86Subtarget.cpp b/llvm/lib/Target/X86/X86Subtarget.cpp
index 493084f..1b02b88 100644
--- a/llvm/lib/Target/X86/X86Subtarget.cpp
+++ b/llvm/lib/Target/X86/X86Subtarget.cpp
@@ -99,6 +99,22 @@
return X86II::MO_GOTOFF;
}
+static bool shouldAssumeGlobalReferenceLocal(const X86Subtarget *ST,
+ const TargetMachine &TM,
+ const Module &M,
+ const GlobalValue *GV) {
+ if (!TM.shouldAssumeDSOLocal(M, GV))
+ return false;
+ // A weak reference can end up being 0. If the code can be more that 4g away
+ // from zero and we are using the small code model we have to treat it as non
+ // local.
+ if (GV && GV->hasExternalWeakLinkage() &&
+ TM.getCodeModel() == CodeModel::Small && TM.isPositionIndependent() &&
+ ST->is64Bit() && ST->isTargetELF())
+ return false;
+ return true;
+}
+
unsigned char X86Subtarget::classifyGlobalReference(const GlobalValue *GV,
const Module &M) const {
// Large model never uses stubs.
@@ -118,7 +134,7 @@
}
}
- if (TM.shouldAssumeDSOLocal(M, GV))
+ if (shouldAssumeGlobalReferenceLocal(this, TM, M, GV))
return classifyLocalReference(GV);
if (isTargetCOFF())