[lld] [lld][COFF] Merge .00cfg section into .rdata. (PR #75207)

[Jacek Caban via llvm-commits]

https://github.com/cjacek created https://github.com/llvm/llvm-project/pull/75207

.00cfg section is used by crt for load config and is merged by MS link.exe into .rdata.

cc @bylaws 

>From ec25a7e0097193143f7da8fa72a2ccc0fcfadaed Mon Sep 17 00:00:00 2001
From: Jacek Caban <jacek at codeweavers.com>
Date: Tue, 12 Dec 2023 16:44:36 +0100
Subject: [PATCH] [lld][COFF] Merge .00cfg section into .rdata.

.00cfg section is used by crt for load config and is merged by MS link.exe into .rdata.
---
 lld/COFF/Driver.cpp                       |  1 +
 lld/test/COFF/Inputs/loadconfig-arm64ec.s |  2 +-
 lld/test/COFF/Inputs/loadconfig-cfg-x64.s |  2 +-
 lld/test/COFF/merge-00cfg.s               | 17 +++++++++++++++++
 4 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 lld/test/COFF/merge-00cfg.s

diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 99c1a60735adc5..d4a2f5767a2e87 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -1940,6 +1940,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   parseMerge(".didat=.rdata");
   parseMerge(".edata=.rdata");
   parseMerge(".xdata=.rdata");
+  parseMerge(".00cfg=.rdata");
   parseMerge(".bss=.data");
 
   if (config->mingw) {
diff --git a/lld/test/COFF/Inputs/loadconfig-arm64ec.s b/lld/test/COFF/Inputs/loadconfig-arm64ec.s
index 8bb5ccfed8ebc8..a270d281095dd6 100644
--- a/lld/test/COFF/Inputs/loadconfig-arm64ec.s
+++ b/lld/test/COFF/Inputs/loadconfig-arm64ec.s
@@ -1,4 +1,4 @@
-        .section .rdata,"dr"
+        .section .00cfg,"dr"
         .globl _load_config_used
         .p2align 3, 0
 _load_config_used:
diff --git a/lld/test/COFF/Inputs/loadconfig-cfg-x64.s b/lld/test/COFF/Inputs/loadconfig-cfg-x64.s
index 1440b115f46ad4..349d8c5a8db36e 100644
--- a/lld/test/COFF/Inputs/loadconfig-cfg-x64.s
+++ b/lld/test/COFF/Inputs/loadconfig-cfg-x64.s
@@ -1,6 +1,6 @@
 # This is the _load_config_used definition needed for /guard:cf tests.
 
-        .section .rdata,"dr"
+        .section .00cfg,"dr"
 .globl _load_config_used
 _load_config_used:
         .long 256
diff --git a/lld/test/COFF/merge-00cfg.s b/lld/test/COFF/merge-00cfg.s
new file mode 100644
index 00000000000000..89a4c8f0834210
--- /dev/null
+++ b/lld/test/COFF/merge-00cfg.s
@@ -0,0 +1,17 @@
+// REQUIRES: x86
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t-x86_64.obj
+// RUN: llvm-mc -filetype=obj -triple=i686-windows %s -o %t-x86.obj
+// RUN: lld-link -machine:amd64 -out:%t-x86_64.dll %t-x86_64.obj -dll -noentry
+// RUN: lld-link -machine:x86 -out:%t-x86.dll %t-x86.obj -dll -noentry -safeseh:no
+
+// RUN: llvm-readobj --hex-dump=.rdata %t-x86_64.dll | FileCheck %s -check-prefix=RDATA
+// RUN: llvm-readobj --hex-dump=.rdata %t-x86.dll | FileCheck %s -check-prefix=RDATA
+// RDATA: 78563412
+
+// RUN: llvm-readobj --sections %t-x86_64.dll | FileCheck %s -check-prefix=SECTIONS
+// RUN: llvm-readobj --sections %t-x86.dll | FileCheck %s -check-prefix=SECTIONS
+// SECTIONS-NOT: .00cfg
+
+        .section ".00cfg", "dr"
+        .long 0x12345678