[lld] Align EC code region boundaries.

[jacek]

Summary

Boundaries between code chunks of different architecture are always aligned. 0x100 seems to be a constant, this does not seem to be affected by any command line alignment argument.

[jacek]

Moving to https://github.com/llvm/llvm-project/pull/69100

lld/COFF/Writer.cpp

for (OutputSection *sec : ctx.outputSections) {
     if (sec == relocSec)
       addBaserels();
     uint64_t rawSize = 0, virtualSize = 0;
     sec->header.VirtualAddress = rva;
 
     // If /FUNCTIONPADMIN is used, functions are padded in order to create a
     // hotpatchable image.
     uint32_t padding = sec->isCodeSection() ? config->functionPadMin : 0;
+    MachineTypes prevECMachine = IMAGE_FILE_MACHINE_UNKNOWN;
 
     for (Chunk *c : sec->chunks) {
+      if (COFF::isArm64EC(ctx.config.machine) && sec->isCodeSection()) {
+        MachineTypes machine = c->getMachine();
+        if (machine != IMAGE_FILE_MACHINE_UNKNOWN) {
+          // We need additional alignment when crossing EC range baudaries.
+          if (prevECMachine != IMAGE_FILE_MACHINE_UNKNOWN &&
+              machine != prevECMachine)
+            virtualSize = alignTo(virtualSize, 4096);
+          prevECMachine = machine;
+        }
+      }
       if (padding && c->isHotPatchable())
         virtualSize += padding;
       virtualSize = alignTo(virtualSize, c->getAlignment());
       c->setRVA(rva + virtualSize);
       virtualSize += c->getSize();
       if (c->hasData)
         rawSize = alignTo(virtualSize, config->fileAlign);
     }

lld/test/COFF/arm64ec-codemap.test

 Test merged sections.
 
 RUN: lld-link -out:testm.dll -machine:arm64ec arm64ec-func-sym.obj x86_64-func-sym.obj \
 RUN:          codemap3.obj loadconfig-arm64ec.obj -dll -noentry -merge:test=.text
 
 RUN: llvm-readobj --coff-load-config testm.dll | FileCheck -check-prefix=CODEMAPM %s
 CODEMAPM:      CodeMap [
 CODEMAPM-NEXT:   0x1000 - 0x1010  ARM64EC
-CODEMAPM-NEXT:   0x2000 - 0x3004  X64
+CODEMAPM-NEXT:   0x2000 - 0x200E  X64
 CODEMAPM-NEXT: ]
 
 RUN: llvm-objdump -d testm.dll | FileCheck -check-prefix=DISASMM %s
 DISASMM:      Disassembly of section .text:
 DISASMM-EMPTY:
 DISASMM-NEXT: 0000000180001000 <.text>:
 DISASMM-NEXT: 180001000: 52800040     mov     w0, #0x2
 DISASMM-NEXT: 180001004: d65f03c0     ret
 DISASMM-NEXT: 180001008: 528000a0     mov     w0, #0x5
 DISASMM-NEXT: 18000100c: d65f03c0     ret
 DISASMM-NEXT:                 ...
 DISASMM-NEXT: 180002000: b8 03 00 00 00               movl    $0x3, %eax
 DISASMM-NEXT: 180002005: c3                           retq
-DISASMM-NEXT:                 ...
-DISASMM-NEXT: 180002ffe: 00 00                        addb    %al, (%rax)
-DISASMM-NEXT: 180003000: b8 06 00 00 00               movl    $0x6, %eax
+DISASMM-NEXT: 180002006: 00 00                        addb    %al, (%rax)
+DISASMM-NEXT: 180002008: b8 06 00 00 00               movl    $0x6, %eax
+DISASMM-NEXT: 18000200d: c3                           retq
 
 #--- arm64-func-sym.s
     .text
     .globl arm64_func_sym
     .p2align 2, 0x0
 arm64_func_sym:
     mov w0, #7
     ret
 
 #--- arm64ec-func-sym.s
     .text
     .globl arm64ec_func_sym
-    .p2align 12, 0x0
+    .p2align 2, 0x0
 arm64ec_func_sym:
     mov w0, #2
     ret
 
     .section test, "xr"
     .globl arm64ec_func_sym2
     .p2align 2, 0x0
 arm64ec_func_sym2:
     mov w0, #5
     ret
 
 #--- x86_64-func-sym.s
     .text
     .globl x86_64_func_sym
-    .p2align 12, 0x0
+    .p2align 2, 0x0
 x86_64_func_sym:
     movl $3, %eax
     retq
 
     .section test, "xr"
     .globl x86_64_func_sym2
-    .p2align 12, 0x0
+    .p2align 2, 0x0
 x86_64_func_sym2:
     movl $6, %eax
     retq
 
 #--- codemap.s
     .section .rdata,"dr"
     .globl code_map
 code_map:

 
 #--- codemap3.s
     .section .rdata,"dr"
     .globl code_map
 code_map:
     .rva arm64ec_func_sym + 1
     .word 16
     .rva x86_64_func_sym + 2
-    .word 0x1004
+    .word 14
 
     .globl code_map_count
 code_map_count = 2