[PATCH] D122097: [BOLT] AArch64: Emit text objects

[Vladislav Khmelevsky via Phabricator via llvm-commits]

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BOLT treats aarch64 objects located in text as empty functions with
contant islands. Emit them with at least 8-byte alignment to the new
text section.

Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D122097

Files:
  bolt/lib/Core/BinaryEmitter.cpp
  bolt/lib/Passes/Aligner.cpp
  bolt/test/runtime/AArch64/text_data.c


Index: bolt/test/runtime/AArch64/text_data.c
===================================================================
--- /dev/null
+++ bolt/test/runtime/AArch64/text_data.c
@@ -0,0 +1,23 @@
+// This test checks that the data object located in text section
+// is properly emitted in the new section.
+
+// RUN: %clang %cflags %s -o %t.exe -Wl,-q
+// RUN: llvm-bolt %t.exe -o %t.bolt -lite=0 -use-old-text=0
+// RUN: %t.bolt
+// RUN: llvm-objdump -j .text -d --disassemble-symbols=arr %t.bolt | \
+// RUN:   FileCheck %s
+
+// CHECK: {{.*}} <arr>:
+
+#include <stdlib.h>
+
+typedef void (*FooPtr)();
+
+void exitOk() { exit(0); }
+
+__attribute__((section(".text"))) const FooPtr arr[] = {exitOk, NULL};
+
+int main() {
+  arr[0]();
+  return -1;
+}
Index: bolt/lib/Passes/Aligner.cpp
===================================================================
--- bolt/lib/Passes/Aligner.cpp
+++ bolt/lib/Passes/Aligner.cpp
@@ -172,6 +172,19 @@
     else
       alignMaxBytes(BF);
 
+    // Align objects that contains constant islands and no code
+    // to at least 8 bytes.
+    if (!BF.size() && BF.hasIslandsInfo()) {
+      if (BF.getAlignment() < sizeof(uint64_t))
+        BF.setAlignment(sizeof(uint64_t));
+
+      if (BF.getMaxAlignmentBytes() < sizeof(uint64_t))
+        BF.setMaxAlignmentBytes(sizeof(uint64_t));
+
+      if (BF.getMaxColdAlignmentBytes() < sizeof(uint64_t))
+        BF.setMaxColdAlignmentBytes(sizeof(uint64_t));
+    }
+
     if (opts::AlignBlocks && !opts::PreserveBlocksAlignment)
       alignBlocks(BF, Emitter.MCE.get());
   };
Index: bolt/lib/Core/BinaryEmitter.cpp
===================================================================
--- bolt/lib/Core/BinaryEmitter.cpp
+++ bolt/lib/Core/BinaryEmitter.cpp
@@ -277,7 +277,7 @@
 }
 
 bool BinaryEmitter::emitFunction(BinaryFunction &Function, bool EmitColdPart) {
-  if (Function.size() == 0)
+  if (Function.size() == 0 && !Function.hasIslandsInfo())
     return false;
 
   if (Function.getState() == BinaryFunction::State::Empty)


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