[JITLink][RISCV] fix the extractBits behavior and add R_RISCV_JAL relocation.

[fourdim]

Summary

This patch supports the R_RISCV_JAL relocation.
Moreover, it will fix the extractBits function's behavior as it extracts Size + 1 bits.
In the test ELF_jal.s:
Before:

Hi: 4294836480
extractBits(Hi, 12, 8): 480

After:

Hi: 4294836480
extractBits(Hi, 12, 8): 224

[StephenFan]

llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp

230

I think R_RISCV_JAL don't need to left shift Value 12 bits.

[jrtc27]

Why is it so hard to go read the LLD code. This is clearly wrong. LLD:

case R_RISCV_JAL: {
  checkInt(loc, static_cast<int64_t>(val) >> 1, 20, rel);
  checkAlignment(loc, val, 2, rel);

  uint32_t insn = read32le(loc) & 0xFFF;
  uint32_t imm20 = extractBits(val, 20, 20) << 31;
  uint32_t imm10_1 = extractBits(val, 10, 1) << 21;
  uint32_t imm11 = extractBits(val, 11, 11) << 20;
  uint32_t imm19_12 = extractBits(val, 19, 12) << 12;
  insn |= imm20 | imm10_1 | imm11 | imm19_12;

  write32le(loc, insn);
  return;
}

[fourdim]

address the comments and include the recent commits.

[fourdim]

Sorry about arc diff issue. I will update it later.

[fourdim]

fix the arc diff issue

[jrtc27]

This comment has been deleted.

llvm/include/llvm/ExecutionEngine/JITLink/riscv.h

47–51 ↗

(On Diff #402320)

This is still all wrong

[jrtc27]

Whoops Phab did its weird thing of forgetting I had already submitted a comment so it got submitted again alongside my new comment

[fourdim]

Address the comments.

[fourdim]

Reverted in the https://github.com/llvm/llvm-project/commit/051f7cdcd2ccfb54f5030e16d0026057d203ddd2 due to build failure.

[fourdim]

Include the recent commits and fix the test.

llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp

case R_RISCV_BRANCH: {
       break;
     }
     case R_RISCV_JAL: {
       int64_t Value = E.getTarget().getAddress() + E.getAddend() - FixupAddress;
       Error AlignmentIssue = checkAlignment(FixupAddress, Value, 2, E);
       if (AlignmentIssue) {
         return AlignmentIssue;
       }
-      uint32_t Hi = Value >> 12;
-      uint32_t Imm20 = extractBits(Hi, 20, 1) << 31;
-      uint32_t Imm10_1 = extractBits(Hi, 1, 10) << 21;
-      uint32_t Imm11 = extractBits(Hi, 11, 1) << 20;
-      uint32_t Imm19_12 = extractBits(Hi, 12, 8) << 12;
+      uint32_t Imm20 = extractBits(Value, 20, 1) << 31;
+      uint32_t Imm10_1 = extractBits(Value, 1, 10) << 21;
+      uint32_t Imm11 = extractBits(Value, 11, 1) << 20;
+      uint32_t Imm19_12 = extractBits(Value, 12, 8) << 12;
       uint32_t RawInstr = *(little32_t *)FixupPtr;
       *(little32_t *)FixupPtr = RawInstr | Imm20 | Imm10_1 | Imm11 | Imm19_12;
       break;
     }
     case R_RISCV_HI20: {
       int64_t Value = (E.getTarget().getAddress() + E.getAddend()).getValue();
       int64_t Hi = Value + 0x800;
       if (LLVM_UNLIKELY(!isInRangeForImmS32(Hi)))

llvm/test/ExecutionEngine/JITLink/RISCV/ELF_jal.s

# Empty main entry point.
         .type   main,@function
 main:
         ret
 
         .size   main, .-main
 
 # Test R_RISCV_JAL
 
-# jitlink-check: decode_operand(test_jal, 1)[19:0] = (external_func - test_jal)[31:12]
+# jitlink-check: decode_operand(test_jal, 1)[31:12] = (external_func - test_jal)[31:12]
   .globl  test_jal
   .p2align  1
   .type  test_jal,@function
 test_jal:
   jal x0, external_func
 
   .size test_jal, .-test_jal