[PATCH] D18611: Check alignment on the final value

[Rafael Ávila de Espíndola via llvm-commits]

rafael created this revision.
rafael added a reviewer: atanasyan.
rafael added a subscriber: llvm-commits.

I don't think this has any real word implications (unless something supports unaligned instructions), but unblocks simplifying the handling of PC relative relocations.

http://reviews.llvm.org/D18611

Files:
  ELF/Target.cpp
  test/ELF/Inputs/mips-align-err.s
  test/ELF/mips-align-err.s

Index: test/ELF/mips-align-err.s
===================================================================
--- /dev/null
+++ test/ELF/mips-align-err.s
@@ -0,0 +1,12 @@
+# REQUIRES: mips
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o \
+# RUN:         -mcpu=mips32r6
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux \
+# RUN:         -mcpu=mips32r6 %S/Inputs/mips-align-err.s -o %t2.o
+# RUN: not ld.lld %t.o %t2.o -o %t.exe 2>&1 | FileCheck %s
+# CHECK: improper alignment for relocation R_MIPS_PC16
+
+        .globl  __start
+__start:
+.zero 1
+        beqc      $5, $6, _foo            # R_MIPS_PC16
Index: test/ELF/Inputs/mips-align-err.s
===================================================================
--- /dev/null
+++ test/ELF/Inputs/mips-align-err.s
@@ -0,0 +1,2 @@
+        .global _foo
+_foo:
Index: ELF/Target.cpp
===================================================================
--- ELF/Target.cpp
+++ ELF/Target.cpp
@@ -1638,9 +1638,9 @@
                              uint64_t SA) {
   uint32_t Mask = 0xffffffff >> (32 - BSIZE);
   uint32_t Instr = read32<E>(Loc);
-  if (SHIFT > 0)
-    checkAlignment<(1 << SHIFT)>(SA, Type);
   int64_t V = SA - P;
+  if (SHIFT > 0)
+    checkAlignment<(1 << SHIFT)>(V, Type);
   checkInt<BSIZE + SHIFT>(V, Type);
   write32<E>(Loc, (Instr & ~Mask) | ((V >> SHIFT) & Mask));
 }


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