[PATCH] D33975: [MachO] Fix codegen of alias of alias.

[Evgenii Stepanov via Phabricator via llvm-commits]

eugenis updated this revision to Diff 101822.
eugenis marked 2 inline comments as done.

Repository:
  rL LLVM

https://reviews.llvm.org/D33975

Files:
  lib/MC/MCExpr.cpp
  test/MC/MachO/alias.s
  test/MC/MachO/variable-exprs.s


Index: test/MC/MachO/variable-exprs.s
===================================================================
--- test/MC/MachO/variable-exprs.s
+++ test/MC/MachO/variable-exprs.s
@@ -110,8 +110,8 @@
 // CHECK-I386:     0x2C 0 2 0 GENERIC_RELOC_VANILLA 0 __data
 // CHECK-I386:     0x28 0 2 0 GENERIC_RELOC_VANILLA 0 __data
 // CHECK-I386:     0x24 0 2 1 GENERIC_RELOC_VANILLA 0 d3
-// CHECK-I386:     0x20 0 2 1 GENERIC_RELOC_VANILLA 0 d2
-// CHECK-I386:     0x1C 0 2 1 GENERIC_RELOC_VANILLA 0 d
+// CHECK-I386:     0x20 0 2 1 GENERIC_RELOC_VANILLA 0 d{{$}}
+// CHECK-I386:     0x1C 0 2 1 GENERIC_RELOC_VANILLA 0 d{{$}}
 // CHECK-I386:     0x18 0 2 n/a GENERIC_RELOC_VANILLA 1 0x5
 // CHECK-I386:     0x14 0 2 0 GENERIC_RELOC_VANILLA 0 __data
 // CHECK-I386:     0x10 0 2 0 GENERIC_RELOC_VANILLA 0 __data
@@ -319,8 +319,8 @@
 // CHECK-X86_64:     0x2C 0 2 1 X86_64_RELOC_UNSIGNED 0 g
 // CHECK-X86_64:     0x28 0 2 1 X86_64_RELOC_UNSIGNED 0 f
 // CHECK-X86_64:     0x24 0 2 1 X86_64_RELOC_UNSIGNED 0 d3
-// CHECK-X86_64:     0x20 0 2 1 X86_64_RELOC_UNSIGNED 0 d2
-// CHECK-X86_64:     0x1C 0 2 1 X86_64_RELOC_UNSIGNED 0 d
+// CHECK-X86_64:     0x20 0 2 1 X86_64_RELOC_UNSIGNED 0 d{{$}}
+// CHECK-X86_64:     0x1C 0 2 1 X86_64_RELOC_UNSIGNED 0 d{{$}}
 // CHECK-X86_64:     0x18 0 2 1 X86_64_RELOC_UNSIGNED 0 a
 // CHECK-X86_64:     0x14 0 2 1 X86_64_RELOC_UNSIGNED 0 e
 // CHECK-X86_64:     0x10 0 2 1 X86_64_RELOC_UNSIGNED 0 b
Index: test/MC/MachO/alias.s
===================================================================
--- /dev/null
+++ test/MC/MachO/alias.s
@@ -0,0 +1,12 @@
+// RUN: llvm-mc -triple x86_64-apple-macosx10.12.0 %s -filetype=obj | llvm-readobj -r | FileCheck %s
+
+l_a:
+l_b = l_a
+l_c = l_b
+        .long l_c
+
+// CHECK:      Relocations [
+// CHECK-NEXT:   Section __text {
+// CHECK-NEXT:     0x0 0 2 1 X86_64_RELOC_UNSIGNED 0 l_c
+// CHECK-NEXT:   }
+// CHECK-NEXT: ]
Index: lib/MC/MCExpr.cpp
===================================================================
--- lib/MC/MCExpr.cpp
+++ lib/MC/MCExpr.cpp
@@ -655,8 +655,12 @@
         // the OS X assembler will completely drop the 4. We should probably
         // include it in the relocation or produce an error if that is not
         // possible.
+        // Allow constant expressions.
         if (!A && !B)
           return true;
+        // Allows aliases with zero offset.
+        if (Res.getConstant() == 0 && (!A || !B))
+          return true;
       }
     }
 


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