[llvm] 1379b15 - [AArch64] Fix the generation of BE Nops

[David Green via llvm-commits]

Author: David Green
Date: 2022-05-20T09:31:00+01:00
New Revision: 1379b150991f70a5782e9a143c2ba5308da1161c

URL: https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c
DIFF: https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c.diff

LOG: [AArch64] Fix the generation of BE Nops

Big endian Nops were being generated as d5 03 20 1f   fnmadd  s21, s30,
s0, s0, getting the bytes of the NOP in the wrong order. This switches
the bytes to not be dependant on the endianness.

Differential Revision: https://reviews.llvm.org/D125980

Added: 
    llvm/test/MC/AArch64/align.s

Modified: 
    llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
index c1188d1c139e5..a57656ffb38bb 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
@@ -471,7 +471,7 @@ bool AArch64AsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
   // We are properly aligned, so write NOPs as requested.
   Count /= 4;
   for (uint64_t i = 0; i != Count; ++i)
-    support::endian::write<uint32_t>(OS, 0xd503201f, Endian);
+    OS.write("\x1f\x20\x03\xd5", 4);
   return true;
 }
 

diff  --git a/llvm/test/MC/AArch64/align.s b/llvm/test/MC/AArch64/align.s
new file mode 100644
index 0000000000000..fa9950f987754
--- /dev/null
+++ b/llvm/test/MC/AArch64/align.s
@@ -0,0 +1,14 @@
+// RUN: llvm-mc -filetype=obj -triple aarch64-none-eabi %s | llvm-objdump -d - | FileCheck %s
+// RUN: llvm-mc -filetype=obj -triple aarch64_be-none-eabi %s | llvm-objdump -d - | FileCheck %s
+
+// CHECK:   0: 00 00 80 d2   mov     x0, #0
+// CHECK:   4: 00 00 80 d2   mov     x0, #0
+// CHECK:   8: 1f 20 03 d5   nop
+// CHECK:   c: 1f 20 03 d5   nop
+// CHECK:  10: 00 00 80 d2   mov     x0, #0
+
+       .text
+       mov x0, #0
+       mov x0, #0
+       .p2align 4
+       mov x0, #0