PowerPC @l, @h and @ha warnings, plus VLE e_li

This patch started off just adding the warnings in tc-ppc.c about
incorrect usage of @l, @h and @ha in instructions that don't have
16-bit D-form fields.  That unfortunately showed up three warnings in
ld/testsuite/ld-powerpc/vle-multiseg.s on instructions like
	e_li r3, IV_table@l+0x00
which was being assembled to
   8:	70 60 00 00 	e_li    r3,0
			a: R_PPC_ADDR16_LO	IV_table
The ADDR16_LO reloc is of course completely bogus on e_li, which has
a split 20-bit signed integer field in bits 0x1f7fff, the low 11 bit
in 0x7ff, the next 5 bits in 0x1f0000, and the high 4 bits in 0x7800.
Applying an ADDR16_LO reloc to the instruction potentially changes
the e_li instruction to e_add2i., e_add2is, e_cmp16i, e_mull2i,
e_cmpl16i, e_cmph16i, e_cmphl16i, e_or2i, e_and2i., e_or2is, e_lis,
e_and2is, or some invalid encodings.

Now there is a relocation that suits e_li, R_PPC_VLE_ADDR20, which was
added 2017-09-05 but I can't see code in gas to generate the
relocation.  In any case, VLE_ADDR20 probably doesn't have the correct
semantics for @l since ideally you'd want an @l to pair with @h or @ha
to generate a 32-bit constant.  Thus @l should only produce a 16-bit
value, I think.  So we need some more relocations to handle e_li it
seems, or as I do in this patch, modify the behaviour of existing
relocations when applied to e_li instructions.

include/
	* opcode/ppc.h (E_OPCODE_MASK, E_LI_MASK, E_LI_INSN): Define.
bfd/
	* elf32-ppc.c (ppc_elf_howto_raw <R_PPC_VLE_ADDR20>): Correct
	mask and shift value.
	(ppc_elf_vle_split16): Use E_OPCODE_MASK.  Handle e_li
	specially.
gas/
	* config/tc-ppc.c (md_assemble): Adjust relocs for VLE before
	TLS tweaks.  Handle e_li.  Warn on unexpected operand field
	for lo16/hi16/ha16 relocs.

1 files changed, 20 insertions, 8 deletions

diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index c31e26e..6b6043a 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -649,8 +649,8 @@ static reloc_howto_type ppc_elf_howto_raw[] = {
        ppc_elf_unhandled_reloc),
 
   /* e_li split20 format.  */
-  HOW (R_PPC_VLE_ADDR20, 2, 20, 0x1f07ff, 16, FALSE, dont,
-       bfd_elf_generic_reloc),
+  HOW (R_PPC_VLE_ADDR20, 2, 20, 0x1f7fff, 0, FALSE, dont,
+       ppc_elf_unhandled_reloc),
 
   HOW (R_PPC_IRELATIVE, 2, 32, 0xffffffff, 0, FALSE, dont,
        ppc_elf_unhandled_reloc),
@@ -3886,10 +3886,10 @@ ppc_elf_vle_split16 (bfd *input_bfd,
 		     split16_format_type split16_format,
 		     bfd_boolean fixup)
 {
-  unsigned int insn, opcode, top5;
+  unsigned int insn, opcode;
 
   insn = bfd_get_32 (input_bfd, loc);
-  opcode = insn & 0xfc00f800;
+  opcode = insn & E_OPCODE_MASK;
   if (opcode == E_OR2I_INSN
       || opcode == E_AND2I_DOT_INSN
       || opcode == E_OR2IS_INSN
@@ -3926,10 +3926,22 @@ ppc_elf_vle_split16 (bfd *input_bfd,
 	       input_bfd, input_section, offset, opcode);
 	}
     }
-  top5 = value & 0xf800;
-  top5 = top5 << (split16_format == split16a_type ? 5 : 10);
-  insn &= (split16_format == split16a_type ? ~0x1f07ff : ~0x3e007ff);
-  insn |= top5;
+  if (split16_format == split16a_type)
+    {
+      insn &= ~((0xf800 << 5) | 0x7ff);
+      insn |= (value & 0xf800) << 5;
+      if ((insn & E_LI_MASK) == E_LI_INSN)
+	{
+	  /* Hack for e_li.  Extend sign.  */
+	  insn &= ~(0xf0000 >> 5);
+	  insn |= (-(value & 0x8000) & 0xf0000) >> 5;
+	}
+    }
+  else
+    {
+      insn &= ~((0xf800 << 10) | 0x7ff);
+      insn |= (value & 0xf800) << 10;
+    }
   insn |= value & 0x7ff;
   bfd_put_32 (input_bfd, insn, loc);
 }