[lld] [RISCV] Disable gp relaxation if part of object unreachable (PR #72655)

[Fangrui Song via llvm-commits]

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@@ -0,0 +1,58 @@
+# REQUIRES: riscv
+# RUN: rm -rf %t && split-file %s %t && cd %t
+
+# RUN: llvm-mc -filetype=obj -triple=riscv32-unknown-elf -mattr=+relax a.s -o rv32.o
+# RUN: llvm-mc -filetype=obj -triple=riscv64-unknown-elf -mattr=+relax a.s -o rv64.o
+
+# RUN: ld.lld --relax-gp --undefined=__global_pointer$ rv32.o lds -o rv32
+# RUN: ld.lld --relax-gp --undefined=__global_pointer$ rv64.o lds -o rv64
+# RUN: llvm-objdump -td -M no-aliases --no-show-raw-insn rv32 | FileCheck %s
+# RUN: llvm-objdump -td -M no-aliases --no-show-raw-insn rv64 | FileCheck %s
+ 
+# CHECK: 00000080 l       .data  {{0+}}08 Var0
+# CHECK: 00001000 l       .data  {{0+}}80 Var1
+# CHECK: 00000815 g       .sdata {{0+}}00 __global_pointer$
+
+# CHECK: <_start>:
+# CHECK-NOT:  lui
+# CHECK-NEXT: lw      a0, -1941(gp)
+# CHECK-NEXT: lw      a1, -1937(gp)
+# CHECK-NEXT: lui     a1, 1
+# CHECK-NEXT: lw      a0, 0(a1)
+# CHECK-NEXT: lw      a1, 124(a1)
+
+#--- a.s
+.global _start
+_start:
+        lui     a1, %hi(Var0)
+        lw      a0, %lo(Var0)(a1)
+        lw      a1, %lo(Var0+4)(a1)
+        lui     a1, %hi(Var1)
+        lw      a0, %lo(Var1)(a1)      # First part is reachable from gp
+        lw      a1, %lo(Var1+124)(a1)  # The second part is not reachable
+
+.section .rodata
+foo:
+  .space 1
+.section .sdata,"aw"
+  .space 1
+.section .data,"aw"
+  .p2align 3
+Var0:
+  .quad 0
+  .size   Var0, 8
+  .space 3960
+  .p2align 7
+Var1:
+  .quad 0
+  .zero 120
+  .size   Var1, 128
+
+#--- lds
+    SECTIONS {
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MaskRay wrote:

Place `SECTIONS` at column 0 and indent the body by 2.

https://github.com/llvm/llvm-project/pull/72655