Load address of external function from its GOT slothjl/got/gcc-5-branch

Load address of external function from its GOT slot for -fno-plt -fno-pic
if assembler and linker support R_386_GOT32X and R_X86_64_GOTPCRELX to
avoid the PLT slot.  R_386_GOT32X and R_X86_64_GOTPCRELX instruct linker
to re-encode the instruction to convert loading function address from its
GOT slot to immediate if the function is defined locally.

gcc/

	PR target/67400
	* config/i386/i386.md (*cmp<mode>_1): Replace
	nonimmediate_operand with ix86_cmp_destination_operand.
	* config/i386/predicates.md (got_slot_operand): New.
	(ix86_cmp_destination_operand): Likewise.
	(x86_64_immediate_operand): Return false if got_slot_operand
	returns true.
	(x86_64_general_operand): Likewise.

gcc/testsuite/

	PR target/67400
	* gcc.target/i386/pr67400-7.c: New test.

3 files changed, 52 insertions, 2 deletions

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 3eb6cf6afd4..e9556ee03c4 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -1228,7 +1228,7 @@
 
 (define_insn "*cmp<mode>_1"
   [(set (reg FLAGS_REG)
-	(compare (match_operand:SWI 0 "nonimmediate_operand" "<r>m,<r>")
+	(compare (match_operand:SWI 0 "ix86_cmp_destination_operand" "<r>m,<r>")
 		 (match_operand:SWI 1 "<general_operand>" "<r><i>,<r>m")))]
   "ix86_match_ccmode (insn, CCmode)"
   "cmp{<imodesuffix>}\t{%1, %0|%0, %1}"
diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
index 4c9a7568c08..2d07ec3dd50 100644
--- a/gcc/config/i386/predicates.md
+++ b/gcc/config/i386/predicates.md
@@ -37,6 +37,38 @@
   (and (match_code "reg")
        (match_test "GENERAL_REG_P (op)")))
 
+;; Return true if OP should be accessed by its GOT slot.
+(define_predicate "got_slot_operand"
+  (match_code "symbol_ref")
+{
+  /* Load address of external function from its GOT slot for -fno-plt
+     -fno-pic if preferred.  */
+  if (!flag_pic && ix86_noplt_operand (op))
+    {
+      if (TARGET_64BIT)
+	return ix86_cmodel == CM_SMALL && HAVE_LD_R_X86_64_GOTPCRELX;
+      else
+	return HAVE_LD_R_386_GOT32X;
+    }
+  return false;
+})
+
+;; Return true if OP is destination operand suitable for cmp
+;; instruction.
+(define_predicate "ix86_cmp_destination_operand"
+  (match_operand 0 "nonimmediate_operand")
+{
+  if (GET_CODE (op) == MEM)
+    {
+      op = ix86_noplt_addr_symbol_rtx (XEXP (op, 0));
+      if (op)
+	/* Don't put the GOT slot on destination since linker
+	   can't re-encode it as immediate operand.  */
+	return !got_slot_operand (op, GET_MODE (op));
+    }
+  return true;
+})
+
 ;; True if the operand is a nonimmediate operand with GENERAL class register.
 (define_predicate "nonimmediate_gr_operand"
   (if_then_else (match_code "reg")
@@ -143,6 +175,9 @@
 (define_predicate "x86_64_immediate_operand"
   (match_code "const_int,symbol_ref,label_ref,const")
 {
+  if (got_slot_operand (op, mode))
+    return false;
+
   if (!TARGET_64BIT)
     return immediate_operand (op, mode);
 
@@ -364,7 +399,8 @@
   (if_then_else (match_test "TARGET_64BIT")
     (ior (match_operand 0 "nonimmediate_operand")
 	 (match_operand 0 "x86_64_immediate_operand"))
-    (match_operand 0 "general_operand")))
+    (and (not (match_operand 0 "got_slot_operand"))
+	 (match_operand 0 "general_operand"))))
 
 ;; Return true if OP is non-VOIDmode general operand representable
 ;; on x86_64.  This predicate is used in sign-extending conversion
diff --git a/gcc/testsuite/gcc.target/i386/pr67400-7.c b/gcc/testsuite/gcc.target/i386/pr67400-7.c
new file mode 100644
index 00000000000..58df4512d0f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67400-7.c
@@ -0,0 +1,14 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fno-plt" } */
+
+extern void bar (void);
+
+int
+__attribute__((regparm(1)))
+foo (void *p)
+{
+  return p == &bar;
+}
+
+/* { dg-final { scan-assembler "cmp\(l|q\)\[ \t\]*bar@GOTPCREL" { target { { ! ia32 } && r_x86_64_gotpcrelx } } } } */
+/* { dg-final { scan-assembler "cmpl\[ \t\]*bar@GOT," { target { ia32 && r_386_got32x } } } } */