[BOLT] Fix references in ignored functions in CFG state

bolt/include/bolt/Core/BinaryFunction.h

@@ -2335,6 +2335,7 @@ class BinaryFunction {
       releaseCFG();
       CurrentState = State::Emitted;
     }
+    clearList(Relocations);
   }
 
   /// Process LSDA information for the function.

bolt/lib/Core/BinaryContext.cpp

@@ -1032,10 +1032,8 @@ void BinaryContext::adjustCodePadding() {
 
     if (!hasValidCodePadding(BF)) {
       if (HasRelocations) {
-        if (opts::Verbosity >= 1) {
-          this->outs() << "BOLT-INFO: function " << BF
-                       << " has invalid padding. Ignoring the function.\n";
-        }
+        this->errs() << "BOLT-WARNING: function " << BF
+                     << " has invalid padding. Ignoring the function\n";
         BF.setIgnored();
       } else {
         BF.setMaxSize(BF.getSize());

bolt/lib/Core/BinaryFunction.cpp

@@ -1531,8 +1531,6 @@ Error BinaryFunction::disassemble() {
   if (uint64_t Offset = getFirstInstructionOffset())
     Labels[Offset] = BC.Ctx->createNamedTempSymbol();
 
-  clearList(Relocations);
-
   if (!IsSimple) {
     clearList(Instructions);
     return createNonFatalBOLTError("");
@@ -3237,16 +3235,26 @@ void BinaryFunction::setTrapOnEntry() {
 }
 
 void BinaryFunction::setIgnored() {
+  IsIgnored = true;
+
   if (opts::processAllFunctions()) {
     // We can accept ignored functions before they've been disassembled.
-    // In that case, they would still get disassembled and emited, but not
+    // In that case, they would still get disassembled and emitted, but not
     // optimized.
-    assert(CurrentState == State::Empty &&
-           "cannot ignore non-empty functions in current mode");
-    IsIgnored = true;
+    if (CurrentState != State::Empty) {
+      BC.errs() << "BOLT-ERROR: cannot ignore non-empty function " << *this
+                << " in current mode\n";
+      exit(1);
+    }
     return;
   }
 
+  IsSimple = false;
+  LLVM_DEBUG(dbgs() << "Ignoring " << getPrintName() << '\n');
+
+  if (CurrentState == State::Empty)
+    return;
+
   clearDisasmState();
 
   // Clear CFG state too.
@@ -3266,9 +3274,11 @@ void BinaryFunction::setIgnored() {
 
   CurrentState = State::Empty;
 
-  IsIgnored = true;
-  IsSimple = false;
-  LLVM_DEBUG(dbgs() << "Ignoring " << getPrintName() << '\n');
+  // Fix external references in the original function body.
+  if (BC.HasRelocations) {
+    LLVM_DEBUG(dbgs() << "Scanning refs in " << *this << '\n');
+    scanExternalRefs();
+  }
 }
 
 void BinaryFunction::duplicateConstantIslands() {
@@ -3755,7 +3765,6 @@ void BinaryFunction::postProcessBranches() {
 
 MCSymbol *BinaryFunction::addEntryPointAtOffset(uint64_t Offset) {
   assert(Offset && "cannot add primary entry point");
-  assert(CurrentState == State::Empty || CurrentState == State::Disassembled);
 
   const uint64_t EntryPointAddress = getAddress() + Offset;
   MCSymbol *LocalSymbol = getOrCreateLocalLabel(EntryPointAddress);
@@ -3764,6 +3773,8 @@ MCSymbol *BinaryFunction::addEntryPointAtOffset(uint64_t Offset) {
   if (EntrySymbol)
     return EntrySymbol;
 
+  assert(CurrentState == State::Empty || CurrentState == State::Disassembled);
+
   if (BinaryData *EntryBD = BC.getBinaryDataAtAddress(EntryPointAddress)) {
     EntrySymbol = EntryBD->getSymbol();
   } else {

bolt/lib/Rewrite/RewriteInstance.cpp

@@ -3433,6 +3433,7 @@ void RewriteInstance::disassembleFunctions() {
         BC->outs() << "BOLT-INFO: could not disassemble function " << Function
                    << ". Will ignore.\n";
       // Forcefully ignore the function.
+      Function.scanExternalRefs();
       Function.setIgnored();
     });
 

bolt/test/AArch64/patch-ignored.s

@@ -0,0 +1,33 @@
+## Check that llvm-bolt patches functions that are getting ignored after their
+## CFG was constructed.
+
+# RUN: %clang %cflags %s -o %t.exe -Wl,-q
+# RUN: llvm-bolt %t.exe -o %t.bolt --force-patch 2>&1 | FileCheck %s
+# RUN: llvm-objdump -d %t.bolt | FileCheck %s --check-prefix=CHECK-OBJDUMP
+
+  .text
+
+## The function is too small to be patched and BOLT is forced to ignore it under
+## --force-patch. Check that the reference to _start is updated.
+# CHECK: BOLT-WARNING: failed to patch entries in unpatchable
+	.globl unpatchable
+  .type unpatchable, %function
+unpatchable:
+  .cfi_startproc
+# CHECK-OBJDUMP:      <unpatchable>:
+# CHECK-OBJDUMP-NEXT: bl {{.*}} <_start>
+  bl _start
+  ret
+  .cfi_endproc
+  .size unpatchable, .-unpatchable
+
+  .globl _start
+  .type _start, %function
+_start:
+  .cfi_startproc
+  cmp  x0, 1
+  b.eq  .L0
+.L0:
+  ret  x30
+  .cfi_endproc
+  .size _start, .-_start

bolt/test/X86/patch-ignored.s

@@ -0,0 +1,44 @@
+## Check that llvm-bolt patches functions that are getting ignored after their
+## CFG was constructed.
+
+# RUN: %clang %cflags %s -o %t.exe -Wl,-q
+# RUN: llvm-bolt %t.exe -o %t.bolt 2>&1 | FileCheck %s
+# RUN: llvm-objdump -d %t.bolt | FileCheck %s --check-prefix=CHECK-OBJDUMP
+
+  .text
+
+## After the CFG is built, the following function will be marked as ignored
+## due to the presence of the internal call.
+# CHECK:      BOLT-WARNING: will skip the following function
+# CHECK-NEXT: internal_call
+	.globl internal_call
+  .type internal_call, %function
+internal_call:
+  .cfi_startproc
+# CHECK-OBJDUMP:      <internal_call>:
+  call .L1
+  jmp .L2
+# CHECK-OBJDUMP:      jmp
+.L1:
+  jmp _start
+# CHECK-OBJDUMP:      jmp
+# CHECK-OBJDUMP-SAME: <_start>
+  ret
+.L2:
+  jmp _start
+# CHECK-OBJDUMP:      jmp
+# CHECK-OBJDUMP-SAME: <_start>
+  .cfi_endproc
+  .size internal_call, .-internal_call
+
+  .globl _start
+  .type _start, %function
+_start:
+  .cfi_startproc
+  cmpq  %rdi, 1
+  jne  .L0
+  movq %rdi, %rax
+.L0:
+  ret
+  .cfi_endproc
+  .size _start, .-_start