[gcc r12-978] Elide expand_constructor if move by pieces is preferred

[gcc r12-978] Elide expand_constructor if move by pieces is preferred

[H.J. Lu]

https://gcc.gnu.org/g:53fb833d635da04f5b44af16bcea1082e7b59e75

commit r12-978-g53fb833d635da04f5b44af16bcea1082e7b59e75
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri May 21 05:16:20 2021 -0700

    Elide expand_constructor if move by pieces is preferred
    
    Elide expand_constructor when the constructor is static storage and not
    mostly zeros and we can move it by pieces prefer to do so since that's
    usually more efficient than performing a series of stores from immediates.
    
    2021-05-21  Richard Biener  <rguenther@suse.de>
                H.J. Lu  <hjl.tools@gmail.com>
    
    gcc/
    
            PR middle-end/90773
            * expr.c (expand_constructor): Elide expand_constructor if
            move by pieces is preferred.
    
    gcc/testsuite/
    
            * gcc.target/i386/pr90773-24.c: New test.
            * gcc.target/i386/pr90773-25.c: Likewise.

Diff:
---
 gcc/expr.c                                 | 13 +++++++++++++
 gcc/testsuite/gcc.target/i386/pr90773-24.c | 23 +++++++++++++++++++++++
 gcc/testsuite/gcc.target/i386/pr90773-25.c | 25 +++++++++++++++++++++++++
 3 files changed, 61 insertions(+)

diff --git a/gcc/expr.c b/gcc/expr.c
index d09ee42e262..ba61eb98b3b 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -8523,6 +8523,19 @@ expand_constructor (tree exp, rtx target, enum expand_modifier modifier,
       return constructor;
     }
 
+  /* If the CTOR is available in static storage and not mostly
+     zeros and we can move it by pieces prefer to do so since
+     that's usually more efficient than performing a series of
+     stores from immediates.  */
+  if (avoid_temp_mem
+      && TREE_STATIC (exp)
+      && TREE_CONSTANT (exp)
+      && tree_fits_uhwi_p (TYPE_SIZE_UNIT (type))
+      && can_move_by_pieces (tree_to_uhwi (TYPE_SIZE_UNIT (type)),
+			     TYPE_ALIGN (type))
+      && ! mostly_zeros_p (exp))
+    return NULL_RTX;
+
   /* Handle calls that pass values in multiple non-contiguous
      locations.  The Irix 6 ABI has examples of this.  */
   if (target == 0 || ! safe_from_p (target, exp, 1)
diff --git a/gcc/testsuite/gcc.target/i386/pr90773-24.c b/gcc/testsuite/gcc.target/i386/pr90773-24.c
new file mode 100644
index 00000000000..7b2ea66dcfc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr90773-24.c
@@ -0,0 +1,23 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-O2 -march=x86-64" } */
+
+struct S
+{
+  long long s1 __attribute__ ((aligned (8)));
+  unsigned s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14;
+};
+
+const struct S array[] = {
+  { 0, 60, 640, 2112543726, 39682, 48, 16, 33, 10, 96, 2, 0, 0, 4 }
+};
+
+void
+foo (struct S *x)
+{
+  x[0] = array[0];
+}
+
+/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, \\(%\[\^,\]+\\)" 1 } } */
+/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 16\\(%\[\^,\]+\\)" 1 } } */
+/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 32\\(%\[\^,\]+\\)" 1 } } */
+/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 48\\(%\[\^,\]+\\)" 1 } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr90773-25.c b/gcc/testsuite/gcc.target/i386/pr90773-25.c
new file mode 100644
index 00000000000..57642ea8d2d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr90773-25.c
@@ -0,0 +1,25 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-O2 -march=x86-64" } */
+
+struct S
+{
+  long long s1 __attribute__ ((aligned (8)));
+  unsigned s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14;
+};
+
+const struct S array[] = {
+  { 0, }
+};
+
+void
+foo (struct S *x)
+{
+  x[0] = array[0];
+}
+
+/* { dg-final { scan-assembler-not "movdqa" } } */
+/* { dg-final { scan-assembler-times "pxor\[\\t \]%xmm\[0-9\]+, %xmm\[0-9\]+" 1 } } */
+/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, \\(%\[\^,\]+\\)" 1 } } */
+/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 16\\(%\[\^,\]+\\)" 1 } } */
+/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 32\\(%\[\^,\]+\\)" 1 } } */
+/* { dg-final { scan-assembler-times "movups\[\\t \]%xmm\[0-9\]+, 48\\(%\[\^,\]+\\)" 1 } } */