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Re: [PATCH][ARM] PR 68143 Properly update memory offsets when expanding setmem

Hi Ramana,

On 17/11/15 12:02, Ramana Radhakrishnan wrote:


On 06/11/15 10:46, Kyrill Tkachov wrote:

Hi all,

In this wrong-code PR the vector setmem expansion and arm_block_set_aligned_vect in particular
use the wrong offset when calling adjust_automodify_address. In the attached testcase during the
initial zeroing out we get two V16QI stores, but they both are recorded by adjust_automodify_address
as modifying x+0 rather than x+0 and x+12 (the total size to be written is 28).

This led to the scheduling pass moving the store from "x.g = 2;" to before the zeroing stores.

This patch fixes the problem by keeping track of the offset to which stores are emitted and
passing it to adjust_automodify_address as appropriate.

 From inspection I see arm_block_set_unaligned_vect also has this issue so I performed the same
fix in that function as well.

Bootstrapped and tested on arm-none-linux-gnueabihf.

Ok for trunk?

This bug appears on GCC 5 too and I'm currently testing this patch there.
Ok to backport to GCC 5 as well?
Thanks,
Kyrill

2015-11-06  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     PR target/68143
     * config/arm/arm.c (arm_block_set_unaligned_vect): Keep track of
     offset from dstbase and use it appropriately in
     adjust_automodify_address.
     (arm_block_set_aligned_vect): Likewise.

2015-11-06  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     PR target/68143
     * gcc.target/arm/pr68143_1.c: New test.

Sorry about the delay in reviewing this. There's nothing arm specific about this test - I'd just put this in gcc.c-torture/execute, there are enough auto-testers with neon on that will show up issues if this starts failing.


Thanks, will do. I was on the fence about whether this should go in torture.
I'll put it there.

Kyrill



Ok with that change.

Ramana


arm-setmem-offset.patch


commit 78c6989a7af1df672ea227057180d79d717ed5f3
Author: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Date:   Wed Oct 28 17:29:18 2015 +0000

     [ARM] Properly update memory offsets when expanding setmem

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 66e8afc..adf3143 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -29268,7 +29268,7 @@ arm_block_set_unaligned_vect (rtx dstbase,
    rtx (*gen_func) (rtx, rtx);
    machine_mode mode;
    unsigned HOST_WIDE_INT v = value;
-
+  unsigned int offset = 0;
    gcc_assert ((align & 0x3) != 0);
    nelt_v8 = GET_MODE_NUNITS (V8QImode);
    nelt_v16 = GET_MODE_NUNITS (V16QImode);
@@ -29289,7 +29289,7 @@ arm_block_set_unaligned_vect (rtx dstbase,
      return false;
dst = copy_addr_to_reg (XEXP (dstbase, 0)); 
-  mem = adjust_automodify_address (dstbase, mode, dst, 0);
+  mem = adjust_automodify_address (dstbase, mode, dst, offset);
v = sext_hwi (v, BITS_PER_WORD); 
    val_elt = GEN_INT (v);
@@ -29306,7 +29306,11 @@ arm_block_set_unaligned_vect (rtx dstbase,
      {
        emit_insn ((*gen_func) (mem, reg));
        if (i + 2 * nelt_mode <= length)
-	emit_insn (gen_add2_insn (dst, GEN_INT (nelt_mode)));
+	{
+	  emit_insn (gen_add2_insn (dst, GEN_INT (nelt_mode)));
+	  offset += nelt_mode;
+	  mem = adjust_automodify_address (dstbase, mode, dst, offset);
+	}
      }
/* If there are not less than nelt_v8 bytes leftover, we must be in 
@@ -29317,6 +29321,9 @@ arm_block_set_unaligned_vect (rtx dstbase,
    if (i + nelt_v8 < length)
      {
        emit_insn (gen_add2_insn (dst, GEN_INT (length - i)));
+      offset += length - i;
+      mem = adjust_automodify_address (dstbase, mode, dst, offset);
+
        /* We are shifting bytes back, set the alignment accordingly.  */
        if ((length & 1) != 0 && align >= 2)
  	set_mem_align (mem, BITS_PER_UNIT);
@@ -29327,12 +29334,13 @@ arm_block_set_unaligned_vect (rtx dstbase,
    else if (i < length && i + nelt_v8 >= length)
      {
        if (mode == V16QImode)
-	{
-	  reg = gen_lowpart (V8QImode, reg);
-	  mem = adjust_automodify_address (dstbase, V8QImode, dst, 0);
-	}
+	reg = gen_lowpart (V8QImode, reg);
+
        emit_insn (gen_add2_insn (dst, GEN_INT ((length - i)
  					      + (nelt_mode - nelt_v8))));
+      offset += (length - i) + (nelt_mode - nelt_v8);
+      mem = adjust_automodify_address (dstbase, V8QImode, dst, offset);
+
        /* We are shifting bytes back, set the alignment accordingly.  */
        if ((length & 1) != 0 && align >= 2)
  	set_mem_align (mem, BITS_PER_UNIT);
@@ -29359,6 +29367,7 @@ arm_block_set_aligned_vect (rtx dstbase,
    rtx rval[MAX_VECT_LEN];
    machine_mode mode;
    unsigned HOST_WIDE_INT v = value;
+  unsigned int offset = 0;
gcc_assert ((align & 0x3) == 0); 
    nelt_v8 = GET_MODE_NUNITS (V8QImode);
@@ -29390,14 +29399,15 @@ arm_block_set_aligned_vect (rtx dstbase,
    /* Handle first 16 bytes specially using vst1:v16qi instruction.  */
    if (mode == V16QImode)
      {
-      mem = adjust_automodify_address (dstbase, mode, dst, 0);
+      mem = adjust_automodify_address (dstbase, mode, dst, offset);
        emit_insn (gen_movmisalignv16qi (mem, reg));
        i += nelt_mode;
        /* Handle (8, 16) bytes leftover using vst1:v16qi again.  */
        if (i + nelt_v8 < length && i + nelt_v16 > length)
  	{
  	  emit_insn (gen_add2_insn (dst, GEN_INT (length - nelt_mode)));
-	  mem = adjust_automodify_address (dstbase, mode, dst, 0);
+	  offset += length - nelt_mode;
+	  mem = adjust_automodify_address (dstbase, mode, dst, offset);
  	  /* We are shifting bytes back, set the alignment accordingly.  */
  	  if ((length & 0x3) == 0)
  	    set_mem_align (mem, BITS_PER_UNIT * 4);
@@ -29419,7 +29429,7 @@ arm_block_set_aligned_vect (rtx dstbase,
    for (; (i + nelt_mode <= length); i += nelt_mode)
      {
        addr = plus_constant (Pmode, dst, i);
-      mem = adjust_automodify_address (dstbase, mode, addr, i);
+      mem = adjust_automodify_address (dstbase, mode, addr, offset + i);
        emit_move_insn (mem, reg);
      }
@@ -29428,8 +29438,8 @@ arm_block_set_aligned_vect (rtx dstbase, 
    if (i + UNITS_PER_WORD == length)
      {
        addr = plus_constant (Pmode, dst, i - UNITS_PER_WORD);
-      mem = adjust_automodify_address (dstbase, mode,
-				       addr, i - UNITS_PER_WORD);
+      offset += i - UNITS_PER_WORD;
+      mem = adjust_automodify_address (dstbase, mode, addr, offset);
        /* We are shifting 4 bytes back, set the alignment accordingly.  */
        if (align > UNITS_PER_WORD)
  	set_mem_align (mem, BITS_PER_UNIT * UNITS_PER_WORD);
@@ -29441,7 +29451,8 @@ arm_block_set_aligned_vect (rtx dstbase,
    else if (i < length)
      {
        emit_insn (gen_add2_insn (dst, GEN_INT (length - nelt_mode)));
-      mem = adjust_automodify_address (dstbase, mode, dst, 0);
+      offset += length - nelt_mode;
+      mem = adjust_automodify_address (dstbase, mode, dst, offset);
        /* We are shifting bytes back, set the alignment accordingly.  */
        if ((length & 1) == 0)
  	set_mem_align (mem, BITS_PER_UNIT * 2);
diff --git a/gcc/testsuite/gcc.target/arm/pr68143_1.c b/gcc/testsuite/gcc.target/arm/pr68143_1.c
new file mode 100644
index 0000000..323473f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/pr68143_1.c
@@ -0,0 +1,36 @@
+/* { dg-do run } */
+/* { dg-require-effective-target arm_neon_hw } */
+/* { dg-options "-O3 -mcpu=cortex-a57" } */
+/* { dg-add-options arm_neon } */
+
+#define NULL 0
+
+struct stuff
+{
+    int a;
+    int b;
+    int c;
+    int d;
+    int e;
+    char *f;
+    int g;
+};
+
+void __attribute__ ((noinline))
+bar (struct stuff *x)
+{
+  if (x->g != 2)
+    __builtin_abort ();
+}
+
+int
+main (int argc, char** argv)
+{
+  struct stuff x = {0, 0, 0, 0, 0, NULL, 0};
+  x.a = 100;
+  x.d = 100;
+  x.g = 2;
+  /* Struct should now look like {100, 0, 0, 100, 0, 0, 0, 2}.  */
+  bar (&x);
+  return 0;
+}
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