96d40df71e
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=4acf8c78e659833be8be047ba2f8561386a11d4b (1994) introduced this behavior: if a fixup symbol is equated to an expression with an undefined symbol, convert the fixup to be against the target symbol. glibc relies on this behavior to perform assembly level indirection ``` asm("memcpy = __GI_memcpy"); // from sysdeps/generic/symbol-hacks.h ... // call memcpy@PLT // The relocation references __GI_memcpy in GNU as, but memcpy in MC (without the patch) memcpy (...); ``` (1) It complements `extern __typeof(memcpy) memcpy asm("__GI_memcpy");` The frontend asm label does not redirect synthesized memcpy in the middle-end. (See D88712 for details) (2) `asm("memcpy = __GI_memcpy");` is in every translation unit, but the memcpy declaration may not be visible in the translation unit where memcpy is synthesized. MC already redirects `memcpy = __GI_memcpy; call memcpy` but not `memcpy = __GI_memcpy; call memcpy@plt`. This patch fixes the latter by allowing MCExpr::evaluateAsRelocatableImpl to evaluate a non-VK_None MCSymbolRefExpr, which is only done after the layout is available. GNU as allows `memcpy = __GI_memcpy+1; call memcpy@PLT` which seems nonsensical, so we don't allow it. `MC/PowerPC/pr38945.s` `NUMBER = 0x6ffffff9; cmpwi 8,NUMBER@l` requires the `symbol@l` form in AsmMatcher, so evaluation needs to be deferred. This is the place whether future simplification may be possible. Note, if we suppress the VM_None evaluation when MCAsmLayout is nullptr, we may lose the `invalid reassignment of non-absolute variable` diagnostic (`ARM/thumb_set-diagnostics.s` and `MC/AsmParser/variables-invalid.s`). We know that this diagnostic is troublesome in some cases (https://github.com/ClangBuiltLinux/linux/issues/1008), so we can consider making simplification in the future. Reviewed By: jyknight Differential Revision: https://reviews.llvm.org/D88625
113 lines
4.3 KiB
ArmAsm
113 lines
4.3 KiB
ArmAsm
// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | llvm-readobj -S --sr - | FileCheck %s
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// Test that we produce the correct relocation.
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.section .pr23272,"aGw",@progbits,pr23272,comdat
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.globl pr23272
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pr23272:
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pr23272_2:
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pr23272_3 = pr23272_2
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.text
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bar:
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movl $bar, %edx # R_X86_64_32
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movq $bar, %rdx # R_X86_64_32S
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movq $bar, bar(%rip) # R_X86_64_32S
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movl bar, %edx # R_X86_64_32S
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movq bar, %rdx # R_X86_64_32S
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.long bar # R_X86_64_32
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leaq foo@GOTTPOFF(%rip), %rax # R_X86_64_GOTTPOFF
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leaq foo@TLSGD(%rip), %rax # R_X86_64_TLSGD
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leaq foo@TPOFF(%rax), %rax # R_X86_64_TPOFF32
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leaq foo@TLSLD(%rip), %rdi # R_X86_64_TLSLD
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leaq foo@dtpoff(%rax), %rcx # R_X86_64_DTPOFF32
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movabs foo@GOT, %rax # R_X86_64_GOT64
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movabs foo@GOTOFF, %rax # R_X86_64_GOTOFF64
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pushq $bar
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movq foo(%rip), %rdx
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leaq foo-bar(%r14),%r14
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addq $bar,%rax # R_X86_64_32S
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.quad foo@DTPOFF
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movabsq $baz@TPOFF, %rax
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.word foo-bar
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.byte foo-bar
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call foo
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leaq -1+foo(%rip), %r11
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leaq _GLOBAL_OFFSET_TABLE_(%rax), %r15
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leaq _GLOBAL_OFFSET_TABLE_(%rip), %r15
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movl $_GLOBAL_OFFSET_TABLE_, %eax
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movabs $_GLOBAL_OFFSET_TABLE_, %rax
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.quad blah@SIZE # R_X86_64_SIZE64
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.quad blah@SIZE + 32 # R_X86_64_SIZE64
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.quad blah@SIZE - 32 # R_X86_64_SIZE64
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movl blah@SIZE, %eax # R_X86_64_SIZE32
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movl blah@SIZE + 32, %eax # R_X86_64_SIZE32
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movl blah@SIZE - 32, %eax # R_X86_64_SIZE32
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.long foo@gotpcrel
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.long foo@plt
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.quad pr23272_2 - pr23272
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.quad pr23272_3 - pr23272
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.global pr24486
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pr24486:
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pr24486_alias = pr24486
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.long pr24486_alias
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.code16
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call pr23771
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.weak weak_sym
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weak_sym:
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.long pr23272-weak_sym
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// CHECK: Section {
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// CHECK: Name: .rela.text
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// CHECK: Relocations [
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// CHECK-NEXT: 0x1 R_X86_64_32 .text
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// CHECK-NEXT: 0x8 R_X86_64_32S .text
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// CHECK-NEXT: 0x13 R_X86_64_32S .text
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// CHECK-NEXT: 0x1A R_X86_64_32S .text
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// CHECK-NEXT: 0x22 R_X86_64_32S .text
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// CHECK-NEXT: 0x26 R_X86_64_32 .text
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// CHECK-NEXT: 0x2D R_X86_64_GOTTPOFF foo 0xFFFFFFFFFFFFFFFC
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// CHECK-NEXT: 0x34 R_X86_64_TLSGD foo 0xFFFFFFFFFFFFFFFC
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// CHECK-NEXT: 0x3B R_X86_64_TPOFF32 foo 0x0
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// CHECK-NEXT: 0x42 R_X86_64_TLSLD foo 0xFFFFFFFFFFFFFFFC
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// CHECK-NEXT: 0x49 R_X86_64_DTPOFF32 foo 0x0
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// CHECK-NEXT: 0x4F R_X86_64_GOT64 foo 0x0
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// CHECK-NEXT: 0x59 R_X86_64_GOTOFF64 foo 0x0
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// CHECK-NEXT: 0x62 R_X86_64_32S .text 0x0
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// CHECK-NEXT: 0x69 R_X86_64_PC32 foo 0xFFFFFFFFFFFFFFFC
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// CHECK-NEXT: 0x70 R_X86_64_PC32 foo 0x70
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// CHECK-NEXT: 0x77 R_X86_64_32S .text 0x0
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// CHECK-NEXT: 0x7B R_X86_64_DTPOFF64 foo 0x0
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// CHECK-NEXT: 0x85 R_X86_64_TPOFF64 baz 0x0
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// CHECK-NEXT: 0x8D R_X86_64_PC16 foo 0x8D
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// CHECK-NEXT: 0x8F R_X86_64_PC8 foo 0x8F
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// CHECK-NEXT: 0x91 R_X86_64_PLT32 foo 0xFFFFFFFFFFFFFFFC
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// CHECK-NEXT: 0x98 R_X86_64_PC32 foo 0xFFFFFFFFFFFFFFFB
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// CHECK-NEXT: 0x9F R_X86_64_GOTPC32 _GLOBAL_OFFSET_TABLE_ 0x3
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// CHECK-NEXT: 0xA6 R_X86_64_GOTPC32 _GLOBAL_OFFSET_TABLE_ 0xFFFFFFFFFFFFFFFC
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// CHECK-NEXT: 0xAB R_X86_64_GOTPC32 _GLOBAL_OFFSET_TABLE_ 0x1
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// CHECK-NEXT: 0xB1 R_X86_64_GOTPC64 _GLOBAL_OFFSET_TABLE_ 0x2
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// CHECK-NEXT: 0xB9 R_X86_64_SIZE64 blah 0x0
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// CHECK-NEXT: 0xC1 R_X86_64_SIZE64 blah 0x20
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// CHECK-NEXT: 0xC9 R_X86_64_SIZE64 blah 0xFFFFFFFFFFFFFFE0
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// CHECK-NEXT: 0xD4 R_X86_64_SIZE32 blah 0x0
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// CHECK-NEXT: 0xDB R_X86_64_SIZE32 blah 0x20
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// CHECK-NEXT: 0xE2 R_X86_64_SIZE32 blah 0xFFFFFFFFFFFFFFE0
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// CHECK-NEXT: 0xE6 R_X86_64_GOTPCREL foo 0x0
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// CHECK-NEXT: 0xEA R_X86_64_PLT32 foo 0x0
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// CHECK-NEXT: 0xFE R_X86_64_32 .text 0xFE
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// CHECK-NEXT: 0x103 R_X86_64_PC16 pr23771 0xFFFFFFFFFFFFFFFE
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// CHECK-NEXT: 0x105 R_X86_64_PC32 pr23272 0x0
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// CHECK-NEXT: ]
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// CHECK-NEXT: }
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