This patch folds a PC-relative vector address that is adjusted with a constant
offset, to fold the constant into the PC-relative address. I moved this code
to be a separate function to make it clearer what the steps were. With patch
V12 #3, address_to_insn_form is now used to validate the address, so we don't
need any new special address validation.
I have build and bootstrapped a compiler on a little endian power8 system, and
there were no regressions in the test suite. Can I check this in to the trunk.
Patch V12 #13 will contain new tests for this optimization.
2020-01-09 Michael Meissner <meiss...@linux.ibm.com>
* config/rs6000/rs6000.c (adjust_vec_address_pcrel): New helper
function to adjust PC-relative vector addresses.
(rs6000_adjust_vec_address): Call adjust_vec_address_pcrel to
handle vectors with PC-relative addresses.
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c (revision 280073)
+++ gcc/config/rs6000/rs6000.c (working copy)
@@ -6767,6 +6767,60 @@ get_vector_offset (rtx mem, rtx element,
return base_tmp;
}
+/* Helper function update PC-relative addresses when we are adjusting a memory
+ address (ADDR) to a vector to point to a scalar field within the vector with
+ a constant offset (ELEMENT_OFFSET). If the address is not valid, we can
+ use the base register temporary (BASE_TMP) to form the address. */
+
+static rtx
+adjust_vec_address_pcrel (rtx addr, rtx element_offset, rtx base_tmp)
+{
+ rtx new_addr = NULL;
+
+ gcc_assert (CONST_INT_P (element_offset));
+
+ if (GET_CODE (addr) == CONST)
+ addr = XEXP (addr, 0);
+
+ if (GET_CODE (addr) == PLUS)
+ {
+ rtx op0 = XEXP (addr, 0);
+ rtx op1 = XEXP (addr, 1);
+
+ if (CONST_INT_P (op1))
+ {
+ HOST_WIDE_INT offset
+ = INTVAL (XEXP (addr, 1)) + INTVAL (element_offset);
+
+ if (offset == 0)
+ new_addr = op0;
+
+ else
+ {
+ rtx plus = gen_rtx_PLUS (Pmode, op0, GEN_INT (offset));
+ new_addr = gen_rtx_CONST (Pmode, plus);
+ }
+ }
+
+ else
+ {
+ emit_move_insn (base_tmp, addr);
+ new_addr = gen_rtx_PLUS (Pmode, base_tmp, element_offset);
+ }
+ }
+
+ else if (SYMBOL_REF_P (addr) || LABEL_REF_P (addr))
+ {
+ rtx plus = gen_rtx_PLUS (Pmode, addr, element_offset);
+ new_addr = gen_rtx_CONST (Pmode, plus);
+ }
+
+ else
+ gcc_unreachable ();
+
+ return new_addr;
+}
+
/* Adjust a memory address (MEM) of a vector type to point to a scalar field
within the vector (ELEMENT) with a mode (SCALAR_MODE). Use a base register
temporary (BASE_TMP) to fixup the address. Return the new memory address
@@ -6803,6 +6857,11 @@ rs6000_adjust_vec_address (rtx scalar_re
else if (REG_P (addr) || SUBREG_P (addr))
new_addr = gen_rtx_PLUS (Pmode, addr, element_offset);
+ /* For references to local static variables, fold a constant offset into the
+ address. */
+ else if (pcrel_local_address (addr, Pmode) && CONST_INT_P (element_offset))
+ new_addr = adjust_vec_address_pcrel (addr, element_offset, base_tmp);
+
/* Optimize D-FORM addresses with constant offset with a constant element, to
include the element offset in the address directly. */
else if (GET_CODE (addr) == PLUS)
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.ibm.com, phone: +1 (978) 899-4797
