[llvm] 996a8b4 - Re-apply "[JITLink][ELF] Add support for ELF::R_X86_64_REX_GOTPCRELX relocation"

[Lang Hames via llvm-commits]

Author: Lang Hames
Date: 2020-10-23T09:48:05-07:00
New Revision: 996a8b42aa2d956c1f8fc1b001bcee543e2ef697

URL: https://github.com/llvm/llvm-project/commit/996a8b42aa2d956c1f8fc1b001bcee543e2ef697
DIFF: https://github.com/llvm/llvm-project/commit/996a8b42aa2d956c1f8fc1b001bcee543e2ef697.diff

LOG: Re-apply "[JITLink][ELF] Add support for ELF::R_X86_64_REX_GOTPCRELX relocation"

This re-applies e2fceec2fd1 with fixes. Apparently we already *do* support
relaxation for ELF, so we need to make sure the test case allocates a slab at
a fixed address, and that the R_X86_64_REX_GOTPCRELX test references an external
that is guaranteed to be out of range.

Added: 
    

Modified: 
    llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
    llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s

Removed: 
    


################################################################################
diff  --git a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
index 40c7d04378e5..c3498935bd2d 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
@@ -232,6 +232,7 @@ class ELFLinkGraphBuilder_x86_64 {
     case ELF::R_X86_64_64:
       return ELF_x86_64_Edges::ELFX86RelocationKind::Pointer64;
     case ELF::R_X86_64_GOTPCREL:
+    case ELF::R_X86_64_REX_GOTPCRELX:
       return ELF_x86_64_Edges::ELFX86RelocationKind::PCRel32GOTLoad;
     }
     return make_error<JITLinkError>("Unsupported x86-64 relocation:" +

diff  --git a/llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s b/llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s
index 0eef11110264..2814dd2b4c8f 100644
--- a/llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s
+++ b/llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s
@@ -1,6 +1,7 @@
 # RUN: rm -rf %t && mkdir -p %t
 # RUN: llvm-mc -triple=x86_64-unknown-linux -position-independent -filetype=obj -o %t/elf_reloc.o %s
-# RUN: llvm-jitlink -noexec -check %s %t/elf_reloc.o
+# RUN: llvm-jitlink -noexec -slab-allocate 100Kb -slab-address 0xfff00000 \
+# RUN:   -define-abs external_data=0x1 -check %s %t/elf_reloc.o
 #
 # Test standard ELF relocations.
 
@@ -39,12 +40,25 @@ test_gotpcrel:
 .Lend_test_gotpcrel:
         .size   test_gotpcrel, .Lend_test_gotpcrel-test_gotpcrel
 
+# Test REX_GOTPCRELX handling. We want to check both the offset to the GOT entry and its
+# contents.
+# jitlink-check: decode_operand(test_rex_gotpcrelx, 4) = \
+# jitlink-check:   got_addr(elf_reloc.o, external_data) - next_pc(test_rex_gotpcrelx)
+
+        .globl test_rex_gotpcrelx
+        .p2align      4, 0x90
+        .type   test_rex_gotpcrelx, at function
+test_rex_gotpcrelx:
+	movq    external_data at GOTPCREL(%rip), %rax
+.Lend_test_rex_gotpcrelx:
+        .size   test_rex_gotpcrelx, .Lend_test_rex_gotpcrelx-test_rex_gotpcrelx
+
         .type   named_data, at object
         .data
-        .p2align        2
+        .p2align        3
 named_data:
-        .long   42
-        .size   named_data, 4
+        .quad   42
+        .size   named_data, 8
 
 # Test BSS / zero-fill section handling.
 # llvm-jitlink: *{4}bss_variable = 0