[PATCH] D107250: [JITLink] Improve extractBits function

[luxufan via Phabricator via llvm-commits]

StephenFan created this revision.
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Address the advice proposed at patch D105429 <https://reviews.llvm.org/D105429> . Use [Low, Low+size) to represent bits.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D107250

Files:
  llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp


Index: llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp
===================================================================
--- llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp
+++ llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp
@@ -57,8 +57,8 @@
       "No HI20 PCREL relocation type be found for LO12 PCREL relocation type");
 }
 
-static uint32_t extractBits(uint64_t Num, unsigned High, unsigned Low) {
-  return (Num & ((1ULL << (High + 1)) - 1)) >> Low;
+static uint32_t extractBits(uint32_t Num, unsigned Low, size_t Size) {
+  return (Num & (((1ULL << (Size + 1)) - 1) << Low)) >> Low;
 }
 
 class ELFJITLinker_riscv : public JITLinker<ELFJITLinker_riscv> {
@@ -128,8 +128,8 @@
       int64_t Value = RelHI20->getTarget().getAddress() +
                       RelHI20->getAddend() - E.getTarget().getAddress();
       int64_t Lo = Value & 0xFFF;
-      uint32_t Imm31_25 = extractBits(Lo, 11, 5) << 25;
-      uint32_t Imm11_7 = extractBits(Lo, 4, 0) << 7;
+      uint32_t Imm31_25 = extractBits(Lo, 5, 7) << 25;
+      uint32_t Imm11_7 = extractBits(Lo, 0, 5) << 7;
       uint32_t RawInstr = *(little32_t *)FixupPtr;
 
       *(little32_t *)FixupPtr = (RawInstr & 0x1FFF07F) | Imm31_25 | Imm11_7;


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