Reland [X86] Respect code models more when determining if a global reference can fit in 32 bits (#75386)

For non-GlobalValue references, the small and medium code models can use
32 bit constants.

For GlobalValue references, use TargetMachine::isLargeGlobalObject().
Look through aliases for determining if a GlobalValue is small or large.
Even the large code model can reference small objects with 32 bit
constants as long as we're in no-pic mode, or if the reference is offset
from the GOT.

Original commit broke the build...

1 files changed, 7 insertions, 1 deletions

diff --git a/llvm/lib/Target/TargetMachine.cpp b/llvm/lib/Target/TargetMachine.cpp
index 5428e14..3f96bd3 100644
--- a/llvm/lib/Target/TargetMachine.cpp
+++ b/llvm/lib/Target/TargetMachine.cpp
@@ -39,10 +39,16 @@ TargetMachine::TargetMachine(const Target &T, StringRef DataLayoutString,
 
 TargetMachine::~TargetMachine() = default;
 
-bool TargetMachine::isLargeGlobalObject(const GlobalObject *GO) const {
+bool TargetMachine::isLargeGlobalValue(const GlobalValue *GVal) const {
   if (getTargetTriple().getArch() != Triple::x86_64)
     return false;
 
+  auto *GO = GVal->getAliaseeObject();
+
+  // Be conservative if we can't find an underlying GlobalObject.
+  if (!GO)
+    return true;
+
   auto *GV = dyn_cast<GlobalVariable>(GO);
 
   // Functions/GlobalIFuncs are only large under the large code model.