re PR target/54589 (struct offset add should be folded into address calculation)

	PR target/54589
	* combine.c (find_split_point): For invalid memory address
	nonobj + obj + const, if reg + obj + const is valid addressing
	mode, split at nonobj.  Use if rather than else if for the
	fallback.  Comment fixes.

	* gcc.target/i386/pr54589.c: New test.

From-SVN: r266707

4 files changed, 78 insertions, 6 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6ce31bf8927..b215a9c6357 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2018-12-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/54589
+	* combine.c (find_split_point): For invalid memory address
+	nonobj + obj + const, if reg + obj + const is valid addressing
+	mode, split at nonobj.  Use if rather than else if for the
+	fallback.  Comment fixes.
+
 2018-11-30  Indu Bhagat  <indu.bhagat@oracle.com>
 
 	* coverage.c (get_coverage_counts): Use from_function_decl for precise
diff --git a/gcc/combine.c b/gcc/combine.c
index ecc83f89bce..7e611399f2c 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -4945,7 +4945,7 @@ find_split_point (rtx *loc, rtx_insn *insn, bool set_src)
 	}
 
       /* If we have a PLUS whose second operand is a constant and the
-	 address is not valid, perhaps will can split it up using
+	 address is not valid, perhaps we can split it up using
 	 the machine-specific way to split large constants.  We use
 	 the first pseudo-reg (one of the virtual regs) as a placeholder;
 	 it will not remain in the result.  */
@@ -4960,7 +4960,7 @@ find_split_point (rtx *loc, rtx_insn *insn, bool set_src)
 
 	  /* This should have produced two insns, each of which sets our
 	     placeholder.  If the source of the second is a valid address,
-	     we can make put both sources together and make a split point
+	     we can put both sources together and make a split point
 	     in the middle.  */
 
 	  if (seq
@@ -5001,14 +5001,51 @@ find_split_point (rtx *loc, rtx_insn *insn, bool set_src)
 		}
 	    }
 
+	  /* If that didn't work and we have a nested plus, like:
+	     ((REG1 * CONST1) + REG2) + CONST2 and (REG1 + REG2) + CONST2
+	     is valid address, try to split (REG1 * CONST1).  */
+	  if (GET_CODE (XEXP (XEXP (x, 0), 0)) == PLUS
+	      && !OBJECT_P (XEXP (XEXP (XEXP (x, 0), 0), 0))
+	      && OBJECT_P (XEXP (XEXP (XEXP (x, 0), 0), 1))
+	      && ! (GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 0)) == SUBREG
+		    && OBJECT_P (SUBREG_REG (XEXP (XEXP (XEXP (x, 0),
+							 0), 0)))))
+	    {
+	      rtx tem = XEXP (XEXP (XEXP (x, 0), 0), 0);
+	      XEXP (XEXP (XEXP (x, 0), 0), 0) = reg;
+	      if (memory_address_addr_space_p (GET_MODE (x), XEXP (x, 0),
+					       MEM_ADDR_SPACE (x)))
+		{
+		  XEXP (XEXP (XEXP (x, 0), 0), 0) = tem;
+		  return &XEXP (XEXP (XEXP (x, 0), 0), 0);
+		}
+	      XEXP (XEXP (XEXP (x, 0), 0), 0) = tem;
+	    }
+	  else if (GET_CODE (XEXP (XEXP (x, 0), 0)) == PLUS
+		   && OBJECT_P (XEXP (XEXP (XEXP (x, 0), 0), 0))
+		   && !OBJECT_P (XEXP (XEXP (XEXP (x, 0), 0), 1))
+		   && ! (GET_CODE (XEXP (XEXP (XEXP (x, 0), 0), 1)) == SUBREG
+			 && OBJECT_P (SUBREG_REG (XEXP (XEXP (XEXP (x, 0),
+							      0), 1)))))
+	    {
+	      rtx tem = XEXP (XEXP (XEXP (x, 0), 0), 1);
+	      XEXP (XEXP (XEXP (x, 0), 0), 1) = reg;
+	      if (memory_address_addr_space_p (GET_MODE (x), XEXP (x, 0),
+					       MEM_ADDR_SPACE (x)))
+		{
+		  XEXP (XEXP (XEXP (x, 0), 0), 1) = tem;
+		  return &XEXP (XEXP (XEXP (x, 0), 0), 1);
+		}
+	      XEXP (XEXP (XEXP (x, 0), 0), 1) = tem;
+	    }
+
 	  /* If that didn't work, perhaps the first operand is complex and
 	     needs to be computed separately, so make a split point there.
 	     This will occur on machines that just support REG + CONST
 	     and have a constant moved through some previous computation.  */
-
-	  else if (!OBJECT_P (XEXP (XEXP (x, 0), 0))
-		   && ! (GET_CODE (XEXP (XEXP (x, 0), 0)) == SUBREG
-			 && OBJECT_P (SUBREG_REG (XEXP (XEXP (x, 0), 0)))))
+	  if (!OBJECT_P (XEXP (XEXP (x, 0), 0))
+	      && ! (GET_CODE (XEXP (XEXP (x, 0), 0)) == SUBREG
+		    && OBJECT_P (SUBREG_REG (XEXP (XEXP (x, 0), 0)))))
 	    return &XEXP (XEXP (x, 0), 0);
 	}
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b48e353d05d..c5ca4be86c4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-12-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/54589
+	* gcc.target/i386/pr54589.c: New test.
+
 2018-11-30  Jakub Jelinek  <jakub@redhat.com>
 
 	PR testsuite/85368
diff --git a/gcc/testsuite/gcc.target/i386/pr54589.c b/gcc/testsuite/gcc.target/i386/pr54589.c
new file mode 100644
index 00000000000..c1032d71c29
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr54589.c
@@ -0,0 +1,22 @@
+/* PR target/54589 */
+/* { dg-do compile { target { *-*-linux* && lp64 } } } */
+/* { dg-options "-O2 -masm=att" } */
+/* { dg-final { scan-assembler "movl\[ \t]+(?:t\\+336\\(%r..\\)|336\\(%r..,%r..\\)), %eax" } } */
+/* { dg-final { scan-assembler "movl\[ \t]+340\\(%r..,%r..\\), %eax" } } */
+/* { dg-final { scan-assembler-times "salq\[^\n\r]*4, %" 2 } } */
+/* { dg-final { scan-assembler-not "addq\[ \t]" } } */
+
+struct S { int a, b, c, d; };
+struct T { struct S e[16]; struct S f[1024]; } t;
+
+int
+foo (unsigned long x)
+{
+  return t.f[x + 5].a;
+}
+
+int
+bar (struct T *x, unsigned long y)
+{
+  return x->f[y + 5].b;
+}