[PATCH] D70362: Fix fatal linker error on R_MIPS_JALR against a local TLS symbol

[Alexander Richardson via Phabricator via llvm-commits]

arichardson updated this revision to Diff 229725.
arichardson added a comment.

Add .set noreorder to avoid excessive nops and make test more readable


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70362/new/

https://reviews.llvm.org/D70362

Files:
  lld/ELF/Arch/Mips.cpp
  lld/test/ELF/tls-r-mips-jalr.s


Index: lld/test/ELF/tls-r-mips-jalr.s
===================================================================
--- /dev/null
+++ lld/test/ELF/tls-r-mips-jalr.s
@@ -0,0 +1,62 @@
+# REQUIRES: mips
+# RUN: llvm-mc -filetype=obj -triple=mips64-none-freebsd %s -o %t.o
+# RUN: ld.lld -shared %t.o -o %t.so
+# RUN: llvm-objdump -d %t.so | FileCheck %s
+## Minimized test case create from the following C source code
+## typedef int (*callback_f)(void);
+## static __thread callback_f callback;
+## void set_callback(callback_f f) {
+##   callback = f;
+## }
+## int test(void) {
+##   return callback();
+## }
+
+	.set	noat
+	.set	noreorder
+	.globl	test                    # -- Begin function test
+	.p2align	3
+	.type	test, at function
+	.ent	test
+test:                                   # @test
+# %bb.0:                                # %entry
+	ld	$t9, %call16(__tls_get_addr)($gp)
+	.reloc .Ltmp1, R_MIPS_JALR, __tls_get_addr
+.Ltmp1:
+	jalr	$t9
+	nop
+	lui	$1, %dtprel_hi(callback)
+	daddu	$1, $1, $2
+	ld	$t9, %dtprel_lo(callback)($1)
+## The following line (creating a R_MIPS_JALR against a TLS symbol)
+## previously caused a linker error:
+## tls-r-mips-jalr.s.tmp.o has an STT_TLS symbol but doesn't have an SHF_TLS section
+	.reloc .Ltmp2, R_MIPS_JALR, callback
+.Ltmp2:
+	jr	$t9
+	nop
+	.end	test
+.Lfunc_end1:
+	.size	test, .Lfunc_end1-test
+
+
+	.type	callback, at object        # @callback
+	.section	.tbss,"awT", at nobits
+	.p2align	3
+callback:
+	.8byte	0
+	.size	callback, 8
+
+## Check that the R_MIPS_JALR relocations did not change jalr to bal:
+# CHECK-LABEL: Disassembly of section .text:
+# CHECK-EMPTY:
+# CHECK-NEXT: test:
+# CHECK-NEXT:    103d0: df 99 80 20                  	ld	$25, -32736($gp)
+# CHECK-NEXT:    103d4: 03 20 f8 09                  	jalr	$25
+# CHECK-NEXT:    103d8: 00 00 00 00                  	nop
+# CHECK-NEXT:    103dc: 3c 01 00 00                  	lui	$1, 0
+# CHECK-NEXT:    103e0: 00 22 08 2d                  	daddu	$1, $1, $2
+# CHECK-NEXT:    103e4: dc 39 80 00                  	ld	$25, -32768($1)
+# CHECK-NEXT:    103e8: 03 20 00 08                  	jr	$25
+# CHECK-NEXT:    103ec: 00 00 00 00                  	nop
+
Index: lld/ELF/Arch/Mips.cpp
===================================================================
--- lld/ELF/Arch/Mips.cpp
+++ lld/ELF/Arch/Mips.cpp
@@ -86,7 +86,10 @@
     // If the target symbol is not preemptible and is not microMIPS,
     // it might be possible to replace jalr/jr instruction by bal/b.
     // It depends on the target symbol's offset.
-    if (!s.isPreemptible && !(s.getVA() & 0x1))
+    // Additionally, we can't optimize references to TLS variables (and
+    // s.getVA() will generate a fatal error for TLS symbols since Out::tlsPhdr
+    // will not have been initialized yet).
+    if (!s.isPreemptible && !s.isTls() && !(s.getVA() & 0x1))
       return R_PC;
     return R_NONE;
   case R_MICROMIPS_JALR:


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