[AArch64][ELF] Section alignment of 4 for AArch64 instruction

The integrated assembler sets a minimum alignment for the .text section of 4. However user defined sections get an alignment of 1. Unlike the GNU assembler which raises the section alignment to 4 if an AArch64 instruction is used, the integrated assembler leaves the alignment at 1

Author: flopop01

llvm/lib/MC/MCParser/ELFAsmParser.cpp

@@ -700,7 +700,6 @@ bool ELFAsmParser::parseSectionArguments(bool IsPush, SMLoc loc) {
       getContext().getELFSection(SectionName, Type, Flags, Size, GroupName,
                                  IsComdat, UniqueID, LinkedToSym);
   getStreamer().switchSection(Section, Subsection);
-
   // Check that flags are used consistently. However, the GNU assembler permits
   // to leave out in subsequent uses of the same sections; for compatibility,
   // do likewise.

llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFStreamer.cpp

@@ -327,7 +327,7 @@ class AArch64ELFStreamer : public MCELFStreamer {
     MCELFStreamer::changeSection(Section, Subsection);
 
     // Section alignment of 4 to match GNU Assembler
-    if (Section->getAlign() < 4) {
+    if ((Section->getAlign() < 4) && Section->isText()) {
       Section->setAlignment(Align(4));
       emitValueToAlignment(Align(4), 0, 1, 0);
     }

llvm/test/MC/AArch64/directive-arch-section-alignment.s

@@ -1,21 +1,44 @@
-// RUN: llvm-mc -triple aarch64-windows -filetype obj -o %t.obj %s
-// RUN: llvm-objdump -d -r %t.obj | FileCheck %s
+// RUN: llvm-mc -triple=aarch64-none-linux-gnu -filetype=obj -o %t.obj %s
+// RUN: llvm-readobj -S --sd %t.obj | FileCheck %s  --check-prefix=CHECK-OBJ
+// RUN: llvm-readelf -s  %t.obj | FileCheck %s --check-prefix=CHECK-ELF
 
 .section sec00, "ax"
+.byte 1
+.section sec01, "ax"
 nop
 nop
-nop
-.section sec01, "ax"
+.section sec02, "ax"
 .balign 4
 nop
 nop
+.section sec03, "ax"
+.byte 0
+.section sec04, "aw"
 nop
+nop
+
+// CHECK-OBJ: Name: sec00
+// CHECK-OBJ-NEXT: Type: SHT_PROGBITS (0x1)
+// CHECK-OBJ-NEXT: Flags [ (0x6)
+// CHECK-OBJ: AddressAlignment: 4
+// CHECK-OBJ: Name: sec01
+// CHECK-OBJ-NEXT: Type: SHT_PROGBITS (0x1)
+// CHECK-OBJ-NEXT: Flags [ (0x6)
+// CHECK-OBJ: AddressAlignment: 4
+// CHECK-OBJ: Name: sec02
+// CHECK-OBJ-NEXT: Type: SHT_PROGBITS (0x1)
+// CHECK-OBJ-NEXT: Flags [ (0x6)
+// CHECK-OBJ: Name: sec03
+// CHECK-OBJ-NEXT: Type: SHT_PROGBITS (0x1)
+// CHECK-OBJ-NEXT: Flags [ (0x6)
+// CHECK-OBJ: AddressAlignment: 4
+// CHECK-OBJ: Name: sec04
+// CHECK-OBJ-NEXT: Type: SHT_PROGBITS (0x1)
+// CHECK-OBJ-NEXT: Flags [ (0x3)
+// CHECK-OBJ: AddressAlignment: 1
 
-// CHECK: 0000000000000000 <sec00>:
-// CHECK-NEXT: 0: d503201f      nop
-// CHECK-NEXT: 4: d503201f      nop
-// CHECK-NEXT: 8: d503201f      nop
-// CHECK: 0000000000000000 <sec01>:
-// CHECK-NEXT: 0: d503201f      nop
-// CHECK-NEXT: 4: d503201f      nop
-// CHECK-NEXT: 8: d503201f      nop
+//CHECK-ELF: sec00             PROGBITS        0000000000000000 000040 000001 00  AX  0   0  4
+//CHECK-ELF-NEXT: sec01             PROGBITS        0000000000000000 000044 000008 00  AX  0   0  4
+//CHECK-ELF-NEXT: sec02             PROGBITS        0000000000000000 00004c 000008 00  AX  0   0  4
+//CHECK-ELF-NEXT: sec03             PROGBITS        0000000000000000 000054 000001 00  AX  0   0  4
+//CHECK-ELF-NEXT: sec04             PROGBITS        0000000000000000 000055 000008 00  WA  0   0  1