Index: config/i386/i386-modes.def
===================================================================
--- config/i386/i386-modes.def	(revision 253855)
+++ config/i386/i386-modes.def	(working copy)
@@ -39,19 +39,22 @@ ADJUST_ALIGNMENT (XF, TARGET_128BIT_LONG_DOUBLE ?
    For the i386, we need separate modes when floating-point
    equality comparisons are being done.
 
-   Add CCNO to indicate comparisons against zero that requires
+   Add CCNO to indicate comparisons against zero that require
    Overflow flag to be unset.  Sign bit test is used instead and
    thus can be used to form "a&b>0" type of tests.
 
-   Add CCGC to indicate comparisons against zero that allows
+   Add CCGC to indicate comparisons against zero that allow
    unspecified garbage in the Carry flag.  This mode is used
    by inc/dec instructions.
 
-   Add CCGOC to indicate comparisons against zero that allows
+   Add CCGOC to indicate comparisons against zero that allow
    unspecified garbage in the Carry and Overflow flag. This
    mode is used to simulate comparisons of (a-b) and (a+b)
    against zero using sub/cmp/add operations.
 
+   Add CCGZ to indicate comparisons that allow unspecified garbage
+   in the Zero flag.  This mode is used in double-word comparisons.
+
    Add CCA to indicate that only the Above flag is valid.
    Add CCC to indicate that only the Carry flag is valid.
    Add CCO to indicate that only the Overflow flag is valid.
@@ -62,6 +65,7 @@ ADJUST_ALIGNMENT (XF, TARGET_128BIT_LONG_DOUBLE ?
 CC_MODE (CCGC);
 CC_MODE (CCGOC);
 CC_MODE (CCNO);
+CC_MODE (CCGZ);
 CC_MODE (CCA);
 CC_MODE (CCC);
 CC_MODE (CCO);
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 253855)
+++ config/i386/i386.c	(working copy)
@@ -16732,6 +16732,7 @@ put_condition_code (enum rtx_code code, machine_mo
   switch (code)
     {
     case EQ:
+      gcc_assert (mode != CCGZmode);
       switch (mode)
 	{
 	case E_CCAmode:
@@ -16755,6 +16756,7 @@ put_condition_code (enum rtx_code code, machine_mo
 	}
       break;
     case NE:
+      gcc_assert (mode != CCGZmode);
       switch (mode)
 	{
 	case E_CCAmode:
@@ -16799,6 +16801,7 @@ put_condition_code (enum rtx_code code, machine_mo
 
 	case E_CCmode:
 	case E_CCGCmode:
+	case E_CCGZmode:
 	  suffix = "l";
 	  break;
 
@@ -16807,7 +16810,7 @@ put_condition_code (enum rtx_code code, machine_mo
 	}
       break;
     case LTU:
-      if (mode == CCmode)
+      if (mode == CCmode || mode == CCGZmode)
 	suffix = "b";
       else if (mode == CCCmode)
 	suffix = fp ? "b" : "c";
@@ -16824,6 +16827,7 @@ put_condition_code (enum rtx_code code, machine_mo
 
 	case E_CCmode:
 	case E_CCGCmode:
+	case E_CCGZmode:
 	  suffix = "ge";
 	  break;
 
@@ -16832,7 +16836,7 @@ put_condition_code (enum rtx_code code, machine_mo
 	}
       break;
     case GEU:
-      if (mode == CCmode)
+      if (mode == CCmode || mode == CCGZmode)
 	suffix = "nb";
       else if (mode == CCCmode)
 	suffix = fp ? "nb" : "nc";
@@ -21469,6 +21473,8 @@ ix86_match_ccmode (rtx insn, machine_mode req_mode
     case E_CCZmode:
       break;
 
+    case E_CCGZmode:
+
     case E_CCAmode:
     case E_CCCmode:
     case E_CCOmode:
@@ -22177,6 +22183,52 @@ ix86_expand_branch (enum rtx_code code, rtx op0, r
 	      break;
 	    }
 
+	/* Emulate comparisons that do not depend on Zero flag with
+	   double-word subtraction.  Note that only Overflow, Sign
+	   and Carry flags are valid, so swap arguments and condition
+	   of comparisons that would otherwise test Zero flag.  */
+
+	switch (code)
+	  {
+	  case LE: case LEU: case GT: case GTU:
+	    std::swap (lo[0], lo[1]);
+	    std::swap (hi[0], hi[1]);
+	    code = swap_condition (code);
+	    /* FALLTHRU */
+
+	  case LT: case LTU: case GE: case GEU:
+	    {
+	      rtx (*cmp_insn) (rtx, rtx);
+	      rtx (*sbb_insn) (rtx, rtx, rtx);
+
+	      if (TARGET_64BIT)
+		cmp_insn = gen_cmpdi_1, sbb_insn = gen_subdi3_carry_ccgz;
+	      else
+		cmp_insn = gen_cmpsi_1, sbb_insn = gen_subsi3_carry_ccgz;
+
+	      if (!nonimmediate_operand (lo[0], submode))
+		lo[0] = force_reg (submode, lo[0]);
+	      if (!x86_64_general_operand (lo[1], submode))
+		lo[1] = force_reg (submode, lo[1]);
+
+	      if (!register_operand (hi[0], submode))
+		hi[0] = force_reg (submode, hi[0]);
+	      if (!x86_64_general_operand (hi[1], submode))
+		hi[1] = force_reg (submode, hi[1]);
+
+	      emit_insn (cmp_insn (lo[0], lo[1]));
+	      emit_insn (sbb_insn (gen_rtx_SCRATCH (submode), hi[0], hi[1]));
+
+	      tmp = gen_rtx_REG (CCGZmode, FLAGS_REG);
+
+	      ix86_expand_branch (code, tmp, const0_rtx, label);
+	      return;
+	    }
+
+	  default:
+	    break;
+	  }
+
 	/* Otherwise, we need two or three jumps.  */
 
 	label2 = gen_label_rtx ();
Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md	(revision 253855)
+++ config/i386/i386.md	(working copy)
@@ -6871,6 +6871,19 @@
    (set_attr "pent_pair" "pu")
    (set_attr "mode" "SI")])
 
+(define_insn "sub<mode>3_carry_ccgz"
+  [(set (reg:CCGZ FLAGS_REG)
+	(compare:CCGZ
+	  (match_operand:DWIH 1 "register_operand" "0")
+	  (plus:DWIH
+	    (ltu:DWIH (reg:CC FLAGS_REG) (const_int 0))
+	    (match_operand:DWIH 2 "x86_64_general_operand" "rme"))))
+   (clobber (match_scratch:DWIH 0 "=r"))]
+  ""
+  "sbb{<imodesuffix>}\t{%2, %0|%0, %2}"
+  [(set_attr "type" "alu")
+   (set_attr "mode" "<MODE>")])
+
 (define_insn "subborrow<mode>"
   [(set (reg:CCC FLAGS_REG)
 	(compare:CCC
Index: config/i386/predicates.md
===================================================================
--- config/i386/predicates.md	(revision 253855)
+++ config/i386/predicates.md	(working copy)
@@ -1329,15 +1329,21 @@
   switch (code)
     {
     case EQ: case NE:
+      if (inmode == CCGZmode)
+	return false;
       return true;
-    case LT: case GE:
+    case GE: case LT:
       if (inmode == CCmode || inmode == CCGCmode
-	  || inmode == CCGOCmode || inmode == CCNOmode)
+	  || inmode == CCGOCmode || inmode == CCNOmode || inmode == CCGZmode)
 	return true;
       return false;
-    case LTU: case GTU: case LEU: case GEU:
-      if (inmode == CCmode || inmode == CCCmode)
+    case GEU: case LTU:
+      if (inmode == CCGZmode)
 	return true;
+      /* FALLTHRU */
+    case GTU: case LEU:
+      if (inmode == CCmode || inmode == CCCmode || inmode == CCGZmode)
+	return true;
       return false;
     case ORDERED: case UNORDERED:
       if (inmode == CCmode)
Index: testsuite/gcc.target/i386/pr82580.c
===================================================================
--- testsuite/gcc.target/i386/pr82580.c	(nonexistent)
+++ testsuite/gcc.target/i386/pr82580.c	(working copy)
@@ -0,0 +1,38 @@
+/* PR target/82580 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+#ifdef __SIZEOF_INT128__
+typedef unsigned __int128 U;
+typedef signed __int128 S;
+#else
+typedef unsigned long long U;
+typedef signed long long S;
+#endif
+void bar (void);
+int f0 (U x, U y) { return x == y; }
+int f1 (U x, U y) { return x != y; }
+int f2 (U x, U y) { return x > y; }
+int f3 (U x, U y) { return x >= y; }
+int f4 (U x, U y) { return x < y; }
+int f5 (U x, U y) { return x <= y; }
+int f6 (S x, S y) { return x == y; }
+int f7 (S x, S y) { return x != y; }
+int f8 (S x, S y) { return x > y; }
+int f9 (S x, S y) { return x >= y; }
+int f10 (S x, S y) { return x < y; }
+int f11 (S x, S y) { return x <= y; }
+void f12 (U x, U y) { if (x == y) bar (); }
+void f13 (U x, U y) { if (x != y) bar (); }
+void f14 (U x, U y) { if (x > y) bar (); }
+void f15 (U x, U y) { if (x >= y) bar (); }
+void f16 (U x, U y) { if (x < y) bar (); }
+void f17 (U x, U y) { if (x <= y) bar (); }
+void f18 (S x, S y) { if (x == y) bar (); }
+void f19 (S x, S y) { if (x != y) bar (); }
+void f20 (S x, S y) { if (x > y) bar (); }
+void f21 (S x, S y) { if (x >= y) bar (); }
+void f22 (S x, S y) { if (x < y) bar (); }
+void f23 (S x, S y) { if (x <= y) bar (); }
+
+/* { dg-final { scan-assembler-times "sbb" 16 } } */
