[CMake] Enable buildings builtins for Darwin as part of runtimes

[phosek]

Summary

This seems to be working fine in my testing so this error check shouldn't be needed.

[beanz]

I'm suspicious that this would work as intended. What builtin libraries get built if your triple is Darwin?

[beanz]

So... Looking at the CMake in compiler-rt, COMPILER_RT_DEFAULT_TARGET_ONLY is only interpreted in a NOT APPLE block, so this would really not behave the way you intend. I think it is better to not support this on Darwin for the time being and provide a hard error rather than behaving incorrectly.

I suspect if you passed in multiple Darwin triples in LLVM_BUILTIN_TARGETS you'd get multiple copies of all the Darwin builtin libraries being built.

[phosek]

In D35346#813474, @beanz wrote:

So... Looking at the CMake in compiler-rt, COMPILER_RT_DEFAULT_TARGET_ONLY is only interpreted in a NOT APPLE block, so this would really not behave the way you intend. I think it is better to not support this on Darwin for the time being and provide a hard error rather than behaving incorrectly.

I suspect if you passed in multiple Darwin triples in LLVM_BUILTIN_TARGETS you'd get multiple copies of all the Darwin builtin libraries being built.

Would it be OK to avoid throwing error in case the $target is default (even on Darwin)? That's all I need at the moment.

lld/trunk/ELF/ScriptParser.cpp

static void moveAbsRight(ExprValue &A, ExprValue &B) {
   if (A.isAbsolute())
     std::swap(A, B);
   if (!B.isAbsolute())
     error(A.Loc + ": at least one side of the expression must be absolute");
 }
 
 static ExprValue add(ExprValue A, ExprValue B) {
   moveAbsRight(A, B);
-  return {A.Sec, A.ForceAbsolute, A.Val + B.getValue(), A.Loc};
+  uint64_t Val = alignTo(A.Val, A.Alignment) + B.getValue();
+  return {A.Sec, A.ForceAbsolute, Val, A.Loc};
 }
 
 static ExprValue sub(ExprValue A, ExprValue B) {
-  return {A.Sec, A.Val - B.getValue(), A.Loc};
+  uint64_t Val = alignTo(A.Val, A.Alignment) - B.getValue();
+  return {A.Sec, Val, A.Loc};
 }
 
 static ExprValue mul(ExprValue A, ExprValue B) {
   return A.getValue() * B.getValue();
 }
 
 static ExprValue div(ExprValue A, ExprValue B) {
   if (uint64_t BV = B.getValue())

lld/trunk/test/ELF/linkerscript/Inputs/symbol-reserved.script

+SECTIONS
+{
+  .text : { *(.text) }
+  PROVIDE_HIDDEN(_end = .);
+}

lld/trunk/test/ELF/linkerscript/symbol-reserved.s

 # SHARED: 0000000000000005 .dynsym 00000000 .hidden newsym
 
 # RUN: echo "PROVIDE_HIDDEN(newsym = ALIGN(__ehdr_start, CONSTANT(MAXPAGESIZE)) + 5);" > %t.script
 # RUN: ld.lld -o %t1 %t.script %t
 # RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=ALIGNED %s
 
 # ALIGNED: 0000000000200005 .text 00000000 .hidden newsym
 
+# RUN: echo "PROVIDE_HIDDEN(newsym = ALIGN(3, 8) + 10);" > %t.script
+# RUN: ld.lld -o %t1 %t.script %t
+# RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=ALIGN-ADD %s
+# ALIGN-ADD: 0000000000000012 *ABS* 00000000 .hidden newsym
+
+# RUN: echo "PROVIDE_HIDDEN(newsym = ALIGN(11, 8) - 10);" > %t.script
+# RUN: ld.lld -o %t1 %t.script %t
+# RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=ALIGN-SUB %s
+# ALIGN-SUB: 0000000000000006 *ABS* 00000000 .hidden newsym
+
+# RUN: echo "PROVIDE_HIDDEN(newsym = ALIGN(_end, CONSTANT(MAXPAGESIZE)) + 5);" > %t.script
+# RUN: ld.lld -o %t1 --script %p/Inputs/symbol-reserved.script %t %t.script
+# RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=RELATIVE-ADD %s
+# RELATIVE-ADD: 0000000000001005 .text 00000000 .hidden newsym
+# RELATIVE-ADD: 0000000000000007 .text 00000000 .hidden _end
+
+# RUN: echo "PROVIDE_HIDDEN(newsym = ALIGN(_end, CONSTANT(MAXPAGESIZE)) - 5);" > %t.script
+# RUN: ld.lld -o %t1 --script %p/Inputs/symbol-reserved.script %t %t.script
+# RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=RELATIVE-SUB %s
+# RELATIVE-SUB: 0000000000000ffb .text 00000000 .hidden newsym
+# RELATIVE-SUB: 0000000000000007 .text 00000000 .hidden _end
+
 .global _start
 _start:
   lea newsym(%rip),%rax