[LongJumpPass] X86 enablement. First attempt.

(cherry picked from FBD8753328)
llvm · Jul 6, 2018 · 64c429d · 64c429d
1 parent b447979
commit 64c429d
Show file tree

Hide file tree

Showing 3 changed files with 97 additions and 3 deletions.
diff --git a/bolt/src/BinaryPassManager.cpp b/bolt/src/BinaryPassManager.cpp
@@ -460,8 +460,7 @@ void BinaryFunctionPassManager::runAllPasses(
   // Thighten branches according to offset differences between branch and
   // targets. No extra instructions after this pass, otherwise we may have
   // relocations out of range and crash during linking.
-  if (BC.isAArch64())
-    Manager.registerPass(llvm::make_unique<LongJmpPass>(PrintLongJmp));
+  Manager.registerPass(llvm::make_unique<LongJmpPass>(PrintLongJmp));
 
   // This pass turns tail calls into jumps which makes them invisible to
   // function reordering. It's unsafe to use any CFG or instruction analysis

diff --git a/bolt/src/Passes/LongJmp.cpp b/bolt/src/Passes/LongJmp.cpp
@@ -368,7 +368,7 @@ bool LongJmpPass::removeOrShrinkStubs(const BinaryContext &BC,
                                       BinaryFunction &Func) {
   bool Modified{false};
 
-  assert(BC.isAArch64() && "Unsupported arch");
+  assert((BC.isAArch64() || BC.isX86()) && "Unsupported arch");
   constexpr auto InsnSize = 4; // AArch64
   // Remove unnecessary stubs for branch targets we know we can fit in the
   // instruction

diff --git a/bolt/src/Target/X86/X86MCPlusBuilder.cpp b/bolt/src/Target/X86/X86MCPlusBuilder.cpp
@@ -2215,6 +2215,13 @@ class X86MCPlusBuilder : public MCPlusBuilder {
     return true;
   }
 
+  void createLongJmp(std::vector<MCInst> &Seq, const MCSymbol *Target,
+                     MCContext *Ctx) const override {
+    MCInst Inst;
+    createUncondBranch(Inst, Target, Ctx);
+    Seq.emplace_back(Inst);
+  }
+
   template <typename Itr>
   std::pair<IndirectBranchType, MCInst *>
   analyzePICJumpTable(Itr II,
@@ -2816,6 +2823,94 @@ class X86MCPlusBuilder : public MCPlusBuilder {
     return true;
   }
 
+  int getPCRelEncodingSize(MCInst &Inst) const override {
+
+    switch (Inst.getOpcode()) {
+    default:
+      llvm_unreachable("Failed to get pcrel encoding size");
+      return 0;
+
+    case X86::TAILJMPd: return 32;
+    case X86::TAILJMPm: return 32;
+
+    case X86::CALL64pcrel32: return 64;
+
+    case X86::JCXZ:   return  8;
+    case X86::JECXZ:  return  8;
+    case X86::JRCXZ:  return  8;
+
+    case X86::JMP_1:  return  8;
+    case X86::JMP_2:  return 16;
+    case X86::JMP_4:  return 32;
+
+    case X86::JE_1:  return  8;
+    case X86::JE_2:  return 16;
+    case X86::JE_4:  return 32;
+    case X86::JNE_1: return  8;
+    case X86::JNE_2: return 16;
+    case X86::JNE_4: return 32;
+
+    case X86::JL_1:  return  8;
+    case X86::JL_2:  return 16;
+    case X86::JL_4:  return 32;
+    case X86::JGE_1: return  8;
+    case X86::JGE_2: return 16;
+    case X86::JGE_4: return 32;
+
+    case X86::JLE_1: return  8;
+    case X86::JLE_2: return 16;
+    case X86::JLE_4: return 32;
+    case X86::JG_1:  return  8;
+    case X86::JG_2:  return 16;
+    case X86::JG_4:  return 32;
+
+    case X86::JB_1:  return  8;
+    case X86::JB_2:  return 16;
+    case X86::JB_4:  return 32;
+    case X86::JAE_1: return  8;
+    case X86::JAE_2: return 16;
+    case X86::JAE_4: return 32;
+
+    case X86::JBE_1: return  8;
+    case X86::JBE_2: return 16;
+    case X86::JBE_4: return 32;
+    case X86::JA_1:  return  8;
+    case X86::JA_2:  return 16;
+    case X86::JA_4:  return 32;
+
+    case X86::JS_1:  return  8;
+    case X86::JS_2:  return 16;
+    case X86::JS_4:  return 32;
+    case X86::JNS_1: return  8;
+    case X86::JNS_2: return 16;
+    case X86::JNS_4: return 32;
+
+    case X86::JP_1:  return  8;
+    case X86::JP_2:  return 16;
+    case X86::JP_4:  return 32;
+    case X86::JNP_1: return  8;
+    case X86::JNP_2: return 16;
+    case X86::JNP_4: return 32;
+
+    case X86::JO_1:  return  8;
+    case X86::JO_2:  return 16;
+    case X86::JO_4:  return 32;
+    case X86::JNO_1: return  8;
+    case X86::JNO_2: return 16;
+    case X86::JNO_4: return 32;
+    }
+  }
+
+  // TODO
+  int getShortJmpEncodingSize() const override {
+    return 16;
+  }
+
+  // TODO
+  int getUncondBranchEncodingSize() const override {
+    return 28;
+  }
+
   unsigned getCanonicalBranchOpcode(unsigned Opcode) const override {
     switch (Opcode) {
     default: