[PATCH] D32907: [ELF] - Fix warnings when LLD compiled using gcc 7.1.0

[George Rimar via Phabricator via llvm-commits]

grimar created this revision.
Herald added subscribers: rengolin, aemerson.

I tried to compile LLD using gcc 7.1.0 and got 2 warnings:

  [1/3] Building CXX object tools/lld/ELF/CMakeFiles/lldELF.dir/Target.cpp.o
  /home/umb/LLVM/llvm/tools/lld/ELF/Target.cpp: In member function ‘virtual void lld::elf::{anonymous}::ARMTargetInfo::relocateOne(uint8_t*, uint32_t, uint64_t) const’:
  /home/umb/LLVM/llvm/tools/lld/ELF/Target.cpp:1897:5: warning: this statement may fall through [-Wimplicit-fallthrough=]
       if ((read32le(Loc) & 0xfe000000) == 0xfa000000)
       ^~
  /home/umb/LLVM/llvm/tools/lld/ELF/Target.cpp:1903:3: note: here
     case R_ARM_JUMP24:
     ^~~~
  /home/umb/LLVM/llvm/tools/lld/ELF/Target.cpp:1935:14: warning: this statement may fall through [-Wimplicit-fallthrough=]
       write16le(Loc + 2, (read16le(Loc + 2) & ~0x1000) | (Val & 1) << 12);
       ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /home/umb/LLVM/llvm/tools/lld/ELF/Target.cpp:1938:3: note: here
     case R_ARM_THM_JUMP24:
     ^~~~

Them can be fixed easily. GCC wants to see "fallthrough" word in a comment that has nothing else. People in the web also uses "/* FALLTHRU */" comment for that. Way used in this patch looks to be consistent with rest LLVM code. Patch fixes the warnings for me.


https://reviews.llvm.org/D32907

Files:
  ELF/Target.cpp


Index: ELF/Target.cpp
===================================================================
--- ELF/Target.cpp
+++ ELF/Target.cpp
@@ -1898,7 +1898,8 @@
       // BLX (always unconditional) instruction to an ARM Target, select an
       // unconditional BL.
       write32le(Loc, 0xeb000000 | (read32le(Loc) & 0x00ffffff));
-  // fall through as BL encoding is shared with B
+  // fallthrough
+  // as BL encoding is shared with B
   case R_ARM_JUMP24:
   case R_ARM_PC24:
   case R_ARM_PLT32:
@@ -1932,7 +1933,8 @@
     }
     // Bit 12 is 0 for BLX, 1 for BL
     write16le(Loc + 2, (read16le(Loc + 2) & ~0x1000) | (Val & 1) << 12);
-  // Fall through as rest of encoding is the same as B.W
+  // fallthrough
+  // as rest of encoding is the same as B.W
   case R_ARM_THM_JUMP24:
     // Encoding B  T4, BL T1, BLX T2: Val = S:I1:I2:imm10:imm11:0
     // FIXME: Use of I1 and I2 require v6T2ops


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