[PATCH] D23031: [LinkerScript] Support OR of FLAGS in PHDR directives

[Rafael Espíndola via llvm-commits]

Just a correction. It looks like bfd supports any expressions in here.
With vanilla bfd I can use

PHDRS
{
  ph_foo PT_LOAD FLAGS(1 + 2);
}
SECTIONS
{
  .text : {*(.dynamic) } : ph_foo
}

But that is not documented or implemented in gold.

I did implement a hackish patch to support any expression (sorry for
the bad coordination). Let me know if you think it is worth it and I
will also implement a patch for supporting | in expressions.

Cheers,
Rafael
-------------- next part --------------
diff --git a/ELF/LinkerScript.cpp b/ELF/LinkerScript.cpp
index 8bb704c..436285e 100644
--- a/ELF/LinkerScript.cpp
+++ b/ELF/LinkerScript.cpp
@@ -645,7 +645,10 @@ void ScriptParser::readPhdrs() {
         PhdrCmd.HasPhdrs = true;
       else if (Tok == "FLAGS") {
         expect("(");
-        next().getAsInteger(0, PhdrCmd.Flags);
+        // Passing 0 for the value of dot is a bit of a hack. A general
+        // expression evaluation should take an environment as an argument.
+        // It is not clear if that is worth it for linker scripts.
+        PhdrCmd.Flags = readExpr()(0);
         expect(")");
       } else
         setError("unexpected header attribute: " + Tok);
diff --git a/test/ELF/linkerscript/linkerscript-phdrs-flags.s b/test/ELF/linkerscript/linkerscript-phdrs-flags.s
index f198d85..d4a08f6 100644
--- a/test/ELF/linkerscript/linkerscript-phdrs-flags.s
+++ b/test/ELF/linkerscript/linkerscript-phdrs-flags.s
@@ -1,6 +1,6 @@
 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
-# RUN: echo "PHDRS {all PT_LOAD FILEHDR PHDRS FLAGS (1);} \
+# RUN: echo "PHDRS {all PT_LOAD FILEHDR PHDRS FLAGS (1 + 0x2);} \
 # RUN:       SECTIONS { \
 # RUN:           . = 0x10000200; \
 # RUN:           .text : {*(.text.*)} :all \
@@ -17,7 +17,8 @@
 # CHECK-NEXT:    PhysicalAddress: 0x10000000
 # CHECK-NEXT:    FileSize: 521
 # CHECK-NEXT:    MemSize: 521
-# CHECK-NEXT:    Flags [ (0x1)
+# CHECK-NEXT:    Flags [
+# CHECK-NEXT:      PF_W (0x2)
 # CHECK-NEXT:      PF_X (0x1)
 # CHECK-NEXT:    ]