[llvm] r362139 - [RuntimeDyld] Apply padding and alignment bumps to all sections with stubs, and

[Lang Hames via llvm-commits]

Author: lhames
Date: Thu May 30 12:59:20 2019
New Revision: 362139

URL: http://llvm.org/viewvc/llvm-project?rev=362139&view=rev
Log:
[RuntimeDyld] Apply padding and alignment bumps to all sections with stubs, and
increase the MachO/x86-64 stub alignment to 8.

Stub alignment should be guaranteed for any section containing RuntimeDyld
stubs/GOT-entries. To do this we should pad and align all sections containing
stubs, not just code sections.

This commit also bumps the MachO/x86-64 stub alignment to 8, so that GOT entries
will be aligned.

Modified:
    llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
    llvm/trunk/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h
    llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s

Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=362139&r1=362138&r2=362139&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Thu May 30 12:59:20 2019
@@ -799,13 +799,12 @@ RuntimeDyldImpl::emitSection(const Objec
     pData = data.data();
   }
 
-  // Code section alignment needs to be at least as high as stub alignment or
-  // padding calculations may by incorrect when the section is remapped to a
-  // higher alignment.
-  if (IsCode) {
+  // If there are any stubs then the section alignment needs to be at least as
+  // high as stub alignment or padding calculations may by incorrect when the
+  // section is remapped.
+  if (StubBufSize != 0) {
     Alignment = std::max(Alignment, getStubAlignment());
-    if (StubBufSize > 0)
-      PaddingSize += getStubAlignment() - 1;
+    PaddingSize += getStubAlignment() - 1;
   }
 
   // Some sections, such as debug info, don't need to be loaded for execution.

Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h?rev=362139&r1=362138&r2=362139&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h Thu May 30 12:59:20 2019
@@ -28,7 +28,7 @@ public:
 
   unsigned getMaxStubSize() const override { return 8; }
 
-  unsigned getStubAlignment() override { return 1; }
+  unsigned getStubAlignment() override { return 8; }
 
   Expected<relocation_iterator>
   processRelocationRef(unsigned SectionID, relocation_iterator RelI,

Modified: llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s?rev=362139&r1=362138&r2=362139&view=diff
==============================================================================
--- llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s (original)
+++ llvm/trunk/test/ExecutionEngine/RuntimeDyld/X86/MachO_x86-64_PIC_relocations.s Thu May 30 12:59:20 2019
@@ -22,8 +22,9 @@ insn2:
 	movl	x(%rip), %eax
 
 # Test PC-rel GOT relocation.
-# Verify both the contents of the GOT entry for y, and that the movq instruction
-# references the correct GOT entry address:
+# Verify the alignment of the GOT entry, the contents of the GOT entry for y,
+# and that the movq instruction references the correct GOT entry address:
+# rtdyld-check: stub_addr(test_x86-64.o/__text, y)[2:0] = 0
 # rtdyld-check: *{8}(stub_addr(test_x86-64.o/__text, y)) = y
 # rtdyld-check: decode_operand(insn3, 4) = stub_addr(test_x86-64.o/__text, y) - next_pc(insn3)
 insn3: