rust195: add a draft fix for LLVM data layout for m68k-unknown-netbsd.

[Havard Eidnes (via pkgsrc-wip) <commit-notify%pkgsrc.org@localhost>]

Module Name:	pkgsrc-wip
Committed By:	Havard Eidnes <he%NetBSD.org@localhost>
Pushed By:	he
Date:		Wed May 27 14:15:08 2026 +0000
Changeset:	44f9039d0c26e79c762bec1eef1eb78740efc61c

Added Files:
	rust195/patches/patch-src_llvm-project_llvm_lib_TargetParser_TargetDataLayout.cpp

Log Message:
rust195: add a draft fix for LLVM data layout for m68k-unknown-netbsd.

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Please note that diffs are not public domain; they are subject to the
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diffstat:
 ...ject_llvm_lib_TargetParser_TargetDataLayout.cpp | 94 ++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diffs:
diff --git a/rust195/patches/patch-src_llvm-project_llvm_lib_TargetParser_TargetDataLayout.cpp b/rust195/patches/patch-src_llvm-project_llvm_lib_TargetParser_TargetDataLayout.cpp
new file mode 100644
index 0000000000..2d7834b49d
--- /dev/null
+++ b/rust195/patches/patch-src_llvm-project_llvm_lib_TargetParser_TargetDataLayout.cpp
@@ -0,0 +1,94 @@
+$NetBSD$
+
+Tweak the data layout for NetBSD/m68k, as per
+https://github.com/llvm/llvm-project/issues/199826
+
+--- src/llvm-project/llvm/lib/TargetParser/TargetDataLayout.cpp.orig	2026-05-27 13:35:30.929852884 +0000
++++ src/llvm-project/llvm/lib/TargetParser/TargetDataLayout.cpp
+@@ -130,15 +130,24 @@ static std::string computeM68kDataLayout
+   // FIXME how to wire it with the used object format?
+   Ret += "-m:e";
+ 
+-  // M68k pointers are always 32 bit wide even for 16-bit CPUs.
+-  // The ABI only specifies 16-bit alignment.
+-  // On at least the 68020+ with a 32-bit bus, there is a performance benefit
+-  // to having 32-bit alignment.
+-  Ret += "-p:32:16:32";
+-
+-  // Bytes do not require special alignment, words are word aligned and
+-  // long words are word aligned at minimum.
+-  Ret += "-i8:8:8-i16:16:16-i32:16:32";
++  // Ref. https://github.com/llvm/llvm-project/issues/199826,
++  // the 16-bit alignment of pointer and i32 is perhaps a linuxism...
++  // For now treat NetBSD specially.
++
++  if (! TT.IsOSNetBSD()) {
++    // M68k pointers are always 32 bit wide even for 16-bit CPUs.
++    // The ABI only specifies 16-bit alignment.
++    // On at least the 68020+ with a 32-bit bus, there is a performance benefit
++    // to having 32-bit alignment.
++    Ret += "-p:32:16:32";
++
++    // Bytes do not require special alignment, words are word aligned and
++    // long words are word aligned at minimum.
++    Ret += "-i8:8:8-i16:16:16-i32:16:32";
++  } else { // NetBSD has 32-bit aligned i32 and pointers:
++    Ret += "-p:32:32:32";
++    Ret += "-i8:8:8-i16:16:16-i32:32:32";
++  }
+ 
+   // FIXME no floats at the moment
+ 
+$NetBSD$
+
+--- src/llvm-project/llvm/lib/TargetParser/TargetDataLayout.cpp.orig	2026-05-27 13:35:30.929852884 +0000
++++ src/llvm-project/llvm/lib/TargetParser/TargetDataLayout.cpp
+@@ -130,22 +130,35 @@ static std::string computeM68kDataLayout
+   // FIXME how to wire it with the used object format?
+   Ret += "-m:e";
+ 
+-  // M68k pointers are always 32 bit wide even for 16-bit CPUs.
+-  // The ABI only specifies 16-bit alignment.
+-  // On at least the 68020+ with a 32-bit bus, there is a performance benefit
+-  // to having 32-bit alignment.
+-  Ret += "-p:32:16:32";
+-
+-  // Bytes do not require special alignment, words are word aligned and
+-  // long words are word aligned at minimum.
+-  Ret += "-i8:8:8-i16:16:16-i32:16:32";
++  // Ref. https://github.com/llvm/llvm-project/issues/199826,
++  // the 16-bit alignment of pointer and i32 is perhaps a linuxism...
++  // For now treat NetBSD specially.
++
++  if (! TT.IsOSNetBSD()) {
++    // M68k pointers are always 32 bit wide even for 16-bit CPUs.
++    // The ABI only specifies 16-bit alignment.
++    // On at least the 68020+ with a 32-bit bus, there is a performance benefit
++    // to having 32-bit alignment.
++    Ret += "-p:32:16:32";
++
++    // Bytes do not require special alignment, words are word aligned and
++    // long words are word aligned at minimum.
++    Ret += "-i8:8:8-i16:16:16-i32:16:32";
+ 
+-  // FIXME no floats at the moment
++    // The registers can hold 8, 16, 32 bits
++    Ret += "-n8:16:32";
+ 
+-  // The registers can hold 8, 16, 32 bits
+-  Ret += "-n8:16:32";
++    Ret += "-a:0:16-S16";
++  } else { // NetBSD has 32-bit aligned i32 and pointers:
++    Ret += "-p:32:32:32";
++    Ret += "-i8:8:8-i16:16:16-i32:32:32";
++    // The registers can hold 8, 16, 32 bits
++    Ret += "-n8:16:32";
++    // object and stack alignment is also different:
++    Ret += "-a:0:32-S32";
++  }
+ 
+-  Ret += "-a:0:16-S16";
++  // FIXME no floats at the moment
+ 
+   return Ret;
+ }