[PATCH] D102776: [CG][X86][NFC] Add option to disable unconditional generation of PLT relocations for jmp/call

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ebrevnov created this revision.
Herald added subscribers: pengfei, hiraditya.
ebrevnov requested review of this revision.
Herald added a project: LLVM.
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D102776

Files:
  llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp


Index: llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
===================================================================
--- llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -24,6 +24,7 @@
 #include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
@@ -34,6 +35,10 @@
 
 #define DEBUG_TYPE "mccodeemitter"
 
+cl::opt<bool> DontGenPLTForDSOLocalCalls(
+    "dont-gen-plt-for-dsolocal-calls", cl::Hidden, cl::init(false),
+    cl::desc("Disables generation of PLT relocations for DSO local symbols"));
+
 namespace {
 
 class X86MCCodeEmitter : public MCCodeEmitter {
@@ -1464,6 +1469,15 @@
   case X86II::RawFrm:
     emitByte(BaseOpcode + OpcodeOffset, OS);
 
+    // Check if unconditional generation of PLT32 relocations for
+    // calls/jumps has been explicitly disabled. This may be useful for cases
+    // when nonstandard linker is used. For example, linking of JITed code is
+    // done in a special way and symbols exported by VM get linked only after
+    // PLT table has already been generated and it's too late to reduce PLT32
+    // relocations.
+    if (DontGenPLTForDSOLocalCalls)
+      break;
+
     if (!STI.hasFeature(X86::Mode64Bit) || !isPCRel32Branch(MI, MCII))
       break;
 


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