Revert "Adjust how variable vector extraction is done."

This reverts commit 428a4feef8594142e5324c0f5cfc8281e43bf75a.
See PR93974.

2 files changed, 29 insertions, 69 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 770b1d7a4ee..86825b16a99 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -119,27 +119,6 @@
 2020-02-23  Peter Bergner <bergner@linux.ibm.com>
 
 	Backport from master
-	2020-02-05  Michael Meissner  <meissner@linux.ibm.com>
-
-	PR target/93568
-	* config/rs6000/rs6000.c (get_vector_offset): Fix Q constraint assert
-	to use "mem".
-
-	Backport from master
-	2020-02-03  Michael Meissner  <meissner@linux.ibm.com>
-
-	* config/rs6000/rs6000.c (get_vector_offset): New helper function
-	to calculate the offset in memory from the start of a vector of a
-	particular element.  Add code to keep the element number in
-	bounds if the element number is variable.
-	(rs6000_adjust_vec_address): Move calculation of offset of the
-	vector element to get_vector_offset.
-	(rs6000_split_vec_extract_var): Do not do the initial AND of
-	element here, move the code to get_vector_offset.
-
-2020-02-23  Peter Bergner <bergner@linux.ibm.com>
-
-	Backport from master
 	2020-01-06  Michael Meissner  <meissner@linux.ibm.com>
 
 	* config/rs6000/vsx.md (vsx_extract_<mode>_var, VSX_D iterator):
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index ce1bd3262d1..87d60078bb0 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -7017,53 +7017,10 @@ rs6000_expand_vector_extract (rtx target, rtx vec, rtx elt)
     }
 }
 
-/* Return the offset within a memory object (MEM) of a vector type to a given
-   element within the vector (ELEMENT) with an element size (SCALAR_SIZE).  If
-   the element is constant, we return a constant integer.
-
-   Otherwise, we use a base register temporary to calculate the offset after
-   masking it to fit within the bounds of the vector and scaling it.  The
-   masking is required by the 64-bit ELF version 2 ABI for the vec_extract
-   built-in function.  */
-
-static rtx
-get_vector_offset (rtx mem, rtx element, rtx base_tmp, unsigned scalar_size)
-{
-  if (CONST_INT_P (element))
-    return GEN_INT (INTVAL (element) * scalar_size);
-
-  /* All insns should use the 'Q' constraint (address is a single register) if
-     the element number is not a constant.  */
-  gcc_assert (satisfies_constraint_Q (mem));
-
-  /* Mask the element to make sure the element number is between 0 and the
-     maximum number of elements - 1 so that we don't generate an address
-     outside the vector.  */
-  rtx num_ele_m1 = GEN_INT (GET_MODE_NUNITS (GET_MODE (mem)) - 1);
-  rtx and_op = gen_rtx_AND (Pmode, element, num_ele_m1);
-  emit_insn (gen_rtx_SET (base_tmp, and_op));
-
-  /* Shift the element to get the byte offset from the element number.  */
-  int shift = exact_log2 (scalar_size);
-  gcc_assert (shift >= 0);
-
-  if (shift > 0)
-    {
-      rtx shift_op = gen_rtx_ASHIFT (Pmode, base_tmp, GEN_INT (shift));
-      emit_insn (gen_rtx_SET (base_tmp, shift_op));
-    }
-
-  return base_tmp;
-}
-
 /* 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
-   that is valid for reads or writes to a given register (SCALAR_REG).
-
-   This function is expected to be called after reload is completed when we are
-   splitting insns.  The temporary BASE_TMP might be set multiple times with
-   this code.  */
+   that is valid for reads or writes to a given register (SCALAR_REG).  */
 
 rtx
 rs6000_adjust_vec_address (rtx scalar_reg,
@@ -7074,6 +7031,7 @@ rs6000_adjust_vec_address (rtx scalar_reg,
 {
   unsigned scalar_size = GET_MODE_SIZE (scalar_mode);
   rtx addr = XEXP (mem, 0);
+  rtx element_offset;
   rtx new_addr;
   bool valid_addr_p;
 
@@ -7082,7 +7040,26 @@ rs6000_adjust_vec_address (rtx scalar_reg,
 
   /* Calculate what we need to add to the address to get the element
      address.  */
-  rtx element_offset = get_vector_offset (mem, element, base_tmp, scalar_size);
+  if (CONST_INT_P (element))
+    element_offset = GEN_INT (INTVAL (element) * scalar_size);
+  else
+    {
+      int byte_shift = exact_log2 (scalar_size);
+      gcc_assert (byte_shift >= 0);
+
+      if (byte_shift == 0)
+	element_offset = element;
+
+      else
+	{
+	  if (TARGET_POWERPC64)
+	    emit_insn (gen_ashldi3 (base_tmp, element, GEN_INT (byte_shift)));
+	  else
+	    emit_insn (gen_ashlsi3 (base_tmp, element, GEN_INT (byte_shift)));
+
+	  element_offset = base_tmp;
+	}
+    }
 
   /* Create the new address pointing to the element within the vector.  If we
      are adding 0, we don't have to change the address.  */
@@ -7217,9 +7194,13 @@ rs6000_split_vec_extract_var (rtx dest, rtx src, rtx element, rtx tmp_gpr,
      systems.  */
   if (MEM_P (src))
     {
-      emit_move_insn (dest,
-		      rs6000_adjust_vec_address (dest, src, element, tmp_gpr,
-						 scalar_mode));
+      int num_elements = GET_MODE_NUNITS (mode);
+      rtx num_ele_m1 = GEN_INT (num_elements - 1);
+
+      emit_insn (gen_anddi3 (element, element, num_ele_m1));
+      gcc_assert (REG_P (tmp_gpr));
+      emit_move_insn (dest, rs6000_adjust_vec_address (dest, src, element,
+						       tmp_gpr, scalar_mode));
       return;
     }