[ELF][RISCV] Add R_RISCV_PC_INDIRECT to isRelExpr()

[MaskRay]

Summary

So that R_RISCV_PCREL_LO12_[IS] are considered as link-time constants in
-pie mode, otherwise there are bogus errors:

ld.lld: error: can't create dynamic relocation R_RISCV_PCREL_LO12_I against symbol: .L0  in readonly segment; recompile object files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in the output

[ruiu]

LGTM

ELF/Relocations.cpp

return oneof<R_GOT, R_GOT_OFF, R_HEXAGON_GOT, R_MIPS_GOT_LOCAL_PAGE,
                R_MIPS_GOT_OFF, R_MIPS_GOT_OFF32, R_AARCH64_GOT_PAGE_PC,
                R_GOT_PC, R_GOTPLT>(Expr);
 }
 
 // True if this expression is of the form Sym - X, where X is a position in the
 // file (PC, or GOT for example).
 static bool isRelExpr(RelExpr Expr) {
   return oneof<R_PC, R_GOTREL, R_GOTPLTREL, R_MIPS_GOTREL, R_PPC64_CALL,
-               R_PPC64_RELAX_TOC, R_AARCH64_PAGE_PC, R_RELAX_GOT_PC>(Expr);
+               R_PPC64_RELAX_TOC, R_AARCH64_PAGE_PC, R_RELAX_GOT_PC,
+               R_RISCV_PC_INDIRECT>(Expr);
 }
 
 // Returns true if a given relocation can be computed at link-time.
 //
 // For instance, we know the offset from a relocation to its target at
 // link-time if the relocation is PC-relative and refers a
 // non-interposable function in the same executable. This function
 // will return true for such relocation.

test/ELF/riscv-pcrel-hilo.s

 # REQUIRES: riscv
 
 # RUN: llvm-mc -filetype=obj -triple=riscv32-unknown-elf -mattr=-relax %s -o %t.rv32.o
 # RUN: llvm-mc -filetype=obj -triple=riscv64-unknown-elf -mattr=-relax %s -o %t.rv64.o
 
 # RUN: ld.lld %t.rv32.o --defsym foo=_start+12 --defsym bar=_start -o %t.rv32
 # RUN: ld.lld %t.rv64.o --defsym foo=_start+12 --defsym bar=_start -o %t.rv64
-# RUN: llvm-objdump -d %t.rv32 | FileCheck %s
-# RUN: llvm-objdump -d %t.rv64 | FileCheck %s
-# CHECK:      17 05 00 00     auipc   a0, 0
-# CHECK-NEXT: 13 05 c5 00     addi    a0, a0, 12
-# CHECK-NEXT: 23 26 05 00     sw      zero, 12(a0)
-# CHECK:      17 05 00 00     auipc   a0, 0
-# CHECK-NEXT: 13 05 45 ff     addi    a0, a0, -12
-# CHECK-NEXT: 23 2a 05 fe     sw      zero, -12(a0)
+# RUN: llvm-objdump -d --no-show-raw-insn %t.rv32 | FileCheck %s
+# RUN: llvm-objdump -d --no-show-raw-insn %t.rv64 | FileCheck %s
+# RUN: ld.lld -pie %t.rv32.o --defsym foo=_start+12 --defsym bar=_start -o %t.rv32
+# RUN: ld.lld -pie %t.rv64.o --defsym foo=_start+12 --defsym bar=_start -o %t.rv64
+# RUN: llvm-objdump -d --no-show-raw-insn %t.rv32 | FileCheck %s
+# RUN: llvm-objdump -d --no-show-raw-insn %t.rv64 | FileCheck %s
+# CHECK:      auipc   a0, 0
+# CHECK-NEXT: addi    a0, a0, 12
+# CHECK-NEXT: sw      zero, 12(a0)
+# CHECK:      auipc   a0, 0
+# CHECK-NEXT: addi    a0, a0, -12
+# CHECK-NEXT: sw      zero, -12(a0)
 
 # RUN: ld.lld %t.rv32.o --defsym foo=_start+0x7ffff7ff --defsym bar=_start+12-0x80000800 -o %t.rv32.limits
 # RUN: ld.lld %t.rv64.o --defsym foo=_start+0x7ffff7ff --defsym bar=_start+12-0x80000800 -o %t.rv64.limits
-# RUN: llvm-objdump -d %t.rv32.limits | FileCheck --check-prefix=LIMITS %s
-# RUN: llvm-objdump -d %t.rv64.limits | FileCheck --check-prefix=LIMITS %s
-# LIMITS:      17 f5 ff 7f     auipc   a0, 524287
-# LIMITS-NEXT: 13 05 f5 7f     addi    a0, a0, 2047
-# LIMITS-NEXT: a3 2f 05 7e     sw      zero, 2047(a0)
-# LIMITS:      17 05 00 80     auipc   a0, 524288
-# LIMITS-NEXT: 13 05 05 80     addi    a0, a0, -2048
-# LIMITS-NEXT: 23 20 05 80     sw      zero, -2048(a0)
+# RUN: llvm-objdump -d --no-show-raw-insn %t.rv32.limits | FileCheck --check-prefix=LIMITS %s
+# RUN: llvm-objdump -d --no-show-raw-insn %t.rv64.limits | FileCheck --check-prefix=LIMITS %s
+# LIMITS:      auipc   a0, 524287
+# LIMITS-NEXT: addi    a0, a0, 2047
+# LIMITS-NEXT: sw      zero, 2047(a0)
+# LIMITS:      auipc   a0, 524288
+# LIMITS-NEXT: addi    a0, a0, -2048
+# LIMITS-NEXT: sw      zero, -2048(a0)
 
 # RUN: ld.lld %t.rv32.o --defsym foo=_start+0x7ffff800 --defsym bar=_start+12-0x80000801 -o %t
 # RUN: not ld.lld %t.rv64.o --defsym foo=_start+0x7ffff800 --defsym bar=_start+12-0x80000801 -o %t 2>&1 | FileCheck --check-prefix=ERROR %s
 # ERROR:      relocation R_RISCV_PCREL_HI20 out of range: 524288 is not in [-524288, 524287]
 # ERROR-NEXT: relocation R_RISCV_PCREL_HI20 out of range: -524289 is not in [-524288, 524287]
 
 .global _start
 _start:
     auipc   a0, %pcrel_hi(foo)
     addi    a0, a0, %pcrel_lo(_start)
     sw      x0, %pcrel_lo(_start)(a0)
 .L1:
     auipc   a0, %pcrel_hi(bar)
     addi    a0, a0, %pcrel_lo(.L1)
     sw      x0, %pcrel_lo(.L1)(a0)