[llvm-objdump] Decrease instruction indentation for non-x86

Place the instruction at the 24th column (0-based indexing), matching
GNU objdump ARM/AArch64/powerpc/etc when the address is low.

This is beneficial for non-x86 targets which have short instruction
lengths.

```
// GNU objdump AArch64
   0:   91001062        add     x2, x3, #0x4
  400078:       91001062        add     x2, x3, #0x4
// llvm-objdump, with this patch
       0: 62 10 00 91   add     x2, x3, #4
  400078: 62 10 00 91   add     x2, x3, #4
// llvm-objdump, if we change to print a word instead of bytes in the future
       0: 91001062      add     x2, x3, #4
  400078: 91001062      add     x2, x3, #4

// GNU objdump Thumb
   0:   bf00            nop

// GNU objdump Power ISA 3.1 64-bit instruction
// 0:   00 00 10 04     plwa    r3,0
// 4:   00 00 60 a4
```

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D81590

diff --git a/llvm/test/tools/llvm-objdump/ELF/AArch64/disassemble-align.s b/llvm/test/tools/llvm-objdump/ELF/AArch64/disassemble-align.s
new file mode 100644 (file)
index 0000000..8ad2042
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/ELF/AArch64/disassemble-align.s
@@ -0,0 +1,12 @@
+# RUN: llvm-mc -filetype=obj -triple=aarch64 %s -o %t
+# RUN: llvm-objdump -d %t | tr '\t' '|' | FileCheck --match-full-lines --strict-whitespace %s
+
+## Use '|' to show where the tabs line up.
+#       CHECK:0000000000000000 <$x.0>:
+#  CHECK-NEXT:       0: 62 10 00 91  |add|x2, x3, #4
+# CHECK-EMPTY:
+#  CHECK-NEXT:0000000000000004 <$d.1>:
+#  CHECK-NEXT:       4:|ff ff 00 00|.word|0x0000ffff
+
+  add x2, x3, #4
+  .word 0xffff

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 70ab0a1..fbc0f01 100644 (file)
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -741,9 +741,11 @@ public:
       dumpBytes(Bytes, OS);
     }
 
-    // The output of printInst starts with a tab. Print some spaces so that
-    // the tab has 1 column and advances to the target tab stop.
-    unsigned TabStop = NoShowRawInsn ? 16 : 40;
+    // The output of printInst starts with a tab. Print some spaces so that the
+    // tab has 1 column and advances to the target tab stop. Give more columns
+    // to x86 which may encode an instruction with many bytes.
+    unsigned TabStop =
+        NoShowRawInsn ? 16 : STI.getTargetTriple().isX86() ? 40 : 24;
     unsigned Column = OS.tell() - Start;
     OS.indent(Column < TabStop - 1 ? TabStop - 1 - Column : 7 - Column % 8);