[committed] [PR99123] inline-asm: Don't use decompose_mem_address to find used hard regs

[Vladimir Makarov via Gcc-patches]

The following patch solves

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99123

The patch was successfully bootstrapped and tested on x86-64



commit b6680c2084521d2612c3a08aa01b274078c4f3e3
Author: Vladimir N. Makarov <vmaka...@redhat.com>
Date:   Wed Feb 24 13:54:10 2021 -0500

    [PR99123] inline-asm: Don't use decompose_mem_address to find used hard regs
    
    Inline asm in question has empty constraint which means anything
    including memory with invalid address.  To check used hard regs we
    used decompose_mem_address which assumes memory with valid address.
    The patch implements the same semantics without assuming valid
    addresses.
    
    gcc/ChangeLog:
    
            PR inline-asm/99123
            * lra-constraints.c (uses_hard_regs_p): Don't use decompose_mem_address.
    
    gcc/testsuite/ChangeLog:
    
            PR inline-asm/99123
            * gcc.target/i386/pr99123.c: New.

diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
index 6a5aa41ed55..51acf7f0701 100644
--- a/gcc/lra-constraints.c
+++ b/gcc/lra-constraints.c
@@ -1904,16 +1904,6 @@ uses_hard_regs_p (rtx x, HARD_REG_SET set)
       return (x_hard_regno >= 0
 	      && overlaps_hard_reg_set_p (set, mode, x_hard_regno));
     }
-  if (MEM_P (x))
-    {
-      struct address_info ad;
-
-      decompose_mem_address (&ad, x);
-      if (ad.base_term != NULL && uses_hard_regs_p (*ad.base_term, set))
-	return true;
-      if (ad.index_term != NULL && uses_hard_regs_p (*ad.index_term, set))
-	return true;
-    }
   fmt = GET_RTX_FORMAT (code);
   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
     {
diff --git a/gcc/testsuite/gcc.target/i386/pr99123.c b/gcc/testsuite/gcc.target/i386/pr99123.c
new file mode 100644
index 00000000000..4f32547d5b8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr99123.c
@@ -0,0 +1,51 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+static inline void *
+baz (void *s, unsigned long c, unsigned int count)
+{
+  int d0, d1;
+  __asm__ __volatile__ (""
+                        : "=&c" (d0), "=&D" (d1)
+                        :"a" (c), "q" (count), "0" (count / 4), "" ((long) s)   /// "1"
+                        :"memory");
+  return s;
+}
+
+struct A
+{
+  unsigned long *a;
+};
+
+inline static void *
+bar (struct A *x, int y)
+{
+  char *ptr;
+
+  ptr = (void *) x->a[y >> 12];
+  ptr += y % (1UL << 12);
+  return (void *) ptr;
+}
+
+int
+foo (struct A *x, unsigned int *y, int z, int u)
+{
+  int a, b, c, d, e;
+
+  z += *y;
+  c = z + u;
+  a = (z >> 12) + 1;
+  do
+    {
+      b = (a << 12);
+      d = b - z;
+      e = c - z;
+      if (e < d)
+        d = e;
+      baz (bar (x, z), 0, d);
+      z = b;
+      a++;
+    }
+  while (z < c);
+  return 0;
+}