[gcc(refs/vendors/ARM/heads/arm-struct-reorg-wip)] internal-fn: Avoid dropping the lhs of some calls [PR94941]

[Tamar Christina]

https://gcc.gnu.org/g:688c8da3eb4cc7482f9844e0e87c11f5003bfbef

commit 688c8da3eb4cc7482f9844e0e87c11f5003bfbef
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Mon May 4 21:22:16 2020 +0100

    internal-fn: Avoid dropping the lhs of some calls [PR94941]
    
    create_output_operand coerces an output operand to the insn's
    predicates, using a suggested rtx location if convenient.
    But if that rtx location is actually required rather than
    optional, the builder of the insn has to emit a move afterwards.
    
    (We could instead add a new interface that does this automatically,
    but that's future work.)
    
    This PR shows that we were failing to emit the move for some of the
    vector load internal functions.  I think there are other routines in
    internal-fn.c that potentially have the same problem, but this patch is
    supposed to be a conservative subset suitable for backporting to GCC 10.
    
    2020-05-04  Richard Sandiford  <richard.sandiford@arm.com>
    
    gcc/
            PR middle-end/94941
            * internal-fn.c (expand_load_lanes_optab_fn): Emit a move if the
            chosen lhs is different from the gcall lhs.
            (expand_mask_load_optab_fn): Likewise.
            (expand_gather_load_optab_fn): Likewise.
    
    gcc/testsuite/
            PR middle-end/94941
            * gcc.target/aarch64/sve/acle/general/unoptimized_1.c: New test.

Diff:
---
 gcc/ChangeLog                                       |  8 ++++++++
 gcc/internal-fn.c                                   |  6 ++++++
 gcc/testsuite/ChangeLog                             |  5 +++++
 .../aarch64/sve/acle/general/unoptimized_1.c        | 21 +++++++++++++++++++++
 4 files changed, 40 insertions(+)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f25256d189f..2e4651174d2 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2020-05-04  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR middle-end/94941
+	* internal-fn.c (expand_load_lanes_optab_fn): Emit a move if the
+	chosen lhs is different from the gcall lhs.
+	(expand_mask_load_optab_fn): Likewise.
+	(expand_gather_load_optab_fn): Likewise.
+
 2020-05-04  Marek Polacek  <polacek@redhat.com>
 
 	Revert:
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index 52d1638917a..5e9aa60721e 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -167,6 +167,8 @@ expand_load_lanes_optab_fn (internal_fn, gcall *stmt, convert_optab optab)
   create_output_operand (&ops[0], target, TYPE_MODE (type));
   create_fixed_operand (&ops[1], mem);
   expand_insn (get_multi_vector_move (type, optab), 2, ops);
+  if (!rtx_equal_p (target, ops[0].value))
+    emit_move_insn (target, ops[0].value);
 }
 
 /* Expand STORE_LANES call STMT using optab OPTAB.  */
@@ -2507,6 +2509,8 @@ expand_mask_load_optab_fn (internal_fn, gcall *stmt, convert_optab optab)
   create_fixed_operand (&ops[1], mem);
   create_input_operand (&ops[2], mask, TYPE_MODE (TREE_TYPE (maskt)));
   expand_insn (icode, 3, ops);
+  if (!rtx_equal_p (target, ops[0].value))
+    emit_move_insn (target, ops[0].value);
 }
 
 #define expand_mask_load_lanes_optab_fn expand_mask_load_optab_fn
@@ -2827,6 +2831,8 @@ expand_gather_load_optab_fn (internal_fn, gcall *stmt, direct_optab optab)
   insn_code icode = convert_optab_handler (optab, TYPE_MODE (TREE_TYPE (lhs)),
 					   TYPE_MODE (TREE_TYPE (offset)));
   expand_insn (icode, i, ops);
+  if (!rtx_equal_p (lhs_rtx, ops[0].value))
+    emit_move_insn (lhs_rtx, ops[0].value);
 }
 
 /* Expand DIVMOD() using:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c6025647734..9109924e2e4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-05-04  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR middle-end/94941
+	* gcc.target/aarch64/sve/acle/general/unoptimized_1.c: New test.
+
 2020-04-30  Martin Jambor  <mjambor@suse.cz>
 
 	PR ipa/94856
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general/unoptimized_1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/unoptimized_1.c
new file mode 100644
index 00000000000..18d73e21a83
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/unoptimized_1.c
@@ -0,0 +1,21 @@
+/* { dg-do run { target aarch64_sve_hw } } */
+
+#include <arm_sve.h>
+
+svfloat32_t
+foo (float *ptr)
+{
+  svbool_t pg = svptrue_pat_b32 (SV_VL1);
+  svfloat32_t res = svld1 (pg, ptr);
+  return res;
+}
+
+int
+main (void)
+{
+  svbool_t pg = svptrue_pat_b32 (SV_VL1);
+  float x[1] = { 1 };
+  if (svptest_any (pg, svcmpne (pg, foo (x), 1.0)))
+    __builtin_abort ();
+  return 0;
+}