[PATCH] PR target/103773: Fix wrong-code with -Oz from pop to memory.

[Roger Sayle]

My apologies for the inconvenience.  The new support for -Oz using
push/pop for small integer constants on x86_64 is only a win/correct
for loading registers.  Fixed by adding !MEM_P tests in the appropriate
locations.

This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
and make -k check with no new failures.  Ok for mainline?


2021-12-21  Roger Sayle  <ro...@nextmovesoftware.com>

gcc/ChangeLog
        PR target/103773
        * config/i386/i386.md (*movdi_internal): Only use short
        push/pop sequence for register (non-memory) destinations.
        (*movsi_internal): Likewise.

gcc/testsuite/ChangeLog
        PR target/103773
        * gcc.target/i386/pr103773.c: New test case.

Roger
--


diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index d25453f..e596f8b 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -2217,7 +2217,8 @@
          if (optimize_size > 1
              && TARGET_64BIT
              && CONST_INT_P (operands[1])
-             && IN_RANGE (INTVAL (operands[1]), -128, 127))
+             && IN_RANGE (INTVAL (operands[1]), -128, 127)
+             && !MEM_P (operands[0]))
            return "push{q}\t%1\n\tpop{q}\t%0";
          return "mov{l}\t{%k1, %k0|%k0, %k1}";
        }
@@ -2440,7 +2441,8 @@
        return "lea{l}\t{%E1, %0|%0, %E1}";
       else if (optimize_size > 1
               && CONST_INT_P (operands[1])
-              && IN_RANGE (INTVAL (operands[1]), -128, 127))
+              && IN_RANGE (INTVAL (operands[1]), -128, 127)
+              && !MEM_P (operands[0]))
        {
          if (TARGET_64BIT)
            return "push{q}\t%1\n\tpop{q}\t%q0";
diff --git a/gcc/testsuite/gcc.target/i386/pr103773.c 
b/gcc/testsuite/gcc.target/i386/pr103773.c
new file mode 100644
index 0000000..1e4b8ce
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr103773.c
@@ -0,0 +1,12 @@
+/* { dg-do run } */
+/* { dg-options "-Oz" } */
+
+unsigned long long x;
+
+int main (void)
+{
+  __builtin_memset (&x, 0xff, 4);
+  if (x != 0xffffffff)
+    __builtin_abort ();
+  return 0;
+}