[Bug target/100736] ICE: unrecognizable insn

["guihaoc at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100736

HaoChen Gui <guihaoc at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |guihaoc at gcc dot gnu.org

--- Comment #2 from HaoChen Gui <guihaoc at gcc dot gnu.org> ---
The root cause of the issue is condition rtx can't be recognized when
finite-math-only is set.
I drafted a patch to modify expand of "bcd<bcd_add_sub>_<code>_<mode>". It
expands as before when finite-math-only is not set. While it expands with a
reverse comparison(le -> ungt, ge -> unlt) when finite-math-only is set.
"rs6000_reverse_compare" is a helper method. The code is extracted from
"rs6000_emit_sCOND".
Any comments? Thanks a lot.

diff --git a/gcc/config/rs6000/altivec.md b/gcc/config/rs6000/altivec.md
index 93d237156d5..e91a1af6805 100644
--- a/gcc/config/rs6000/altivec.md
+++ b/gcc/config/rs6000/altivec.md
@@ -4415,7 +4415,7 @@ (define_insn "bcd<bcd_add_sub>_<mode>"
 ;; UNORDERED test on an integer type (like V1TImode) is not defined.  The type
 ;; probably should be one that can go in the VMX (Altivec) registers, so we
 ;; can't use DDmode or DFmode.
-(define_insn "*bcd<bcd_add_sub>_test_<mode>"
+(define_insn "bcd<bcd_add_sub>_test_<mode>"
   [(set (reg:CCFP CR6_REGNO)
        (compare:CCFP
         (unspec:V2DF [(match_operand:VBCD 1 "register_operand" "v")
@@ -4542,6 +4542,18 @@ (define_expand "bcd<bcd_add_sub>_<code>_<mode>"
   "TARGET_P8_VECTOR"
 {
   operands[4] = CONST0_RTX (V2DFmode);
+  emit_insn (gen_bcd<bcd_add_sub>_test_<mode> (operands[0], operands[1],
+                                              operands[2], operands[3],
+                                              operands[4]));
+  rtx cr6 = gen_rtx_REG (CCFPmode, CR6_REGNO);
+  rtx condition_rtx = gen_rtx_<CODE> (SImode, cr6, const0_rtx);
+  if (flag_finite_math_only)
+    {
+      condition_rtx = rs6000_reverse_compare (condition_rtx);
+      PUT_MODE (condition_rtx, SImode);
+    }
+  emit_insn (gen_rtx_SET (operands[0], condition_rtx));
+  DONE;
 })

 (define_insn "*bcdinvalid_<mode>"
diff --git a/gcc/config/rs6000/rs6000-protos.h
b/gcc/config/rs6000/rs6000-protos.h
index 14f6b313105..9b93e26bec2 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -114,6 +114,7 @@ extern enum rtx_code rs6000_reverse_condition
(machine_mode,
 extern rtx rs6000_emit_eqne (machine_mode, rtx, rtx, rtx);
 extern rtx rs6000_emit_fp_cror (rtx_code, machine_mode, rtx);
 extern void rs6000_emit_sCOND (machine_mode, rtx[]);
+extern rtx rs6000_reverse_compare (rtx);
 extern void rs6000_emit_cbranch (machine_mode, rtx[]);
 extern char * output_cbranch (rtx, const char *, int, rtx_insn *);
 extern const char * output_probe_stack_range (rtx, rtx, rtx);
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index ad860728169..39a36add08f 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -15690,19 +15690,14 @@ rs6000_emit_fp_cror (rtx_code code, machine_mode
mode, rtx x)
   return cc;
 }

-void
-rs6000_emit_sCOND (machine_mode mode, rtx operands[])
+rtx
+rs6000_reverse_compare (rtx condition_rtx)
 {
-  rtx condition_rtx = rs6000_generate_compare (operands[1], mode);
   rtx_code cond_code = GET_CODE (condition_rtx);
-
-  if (FLOAT_MODE_P (mode) && HONOR_NANS (mode)
-      && !(FLOAT128_VECTOR_P (mode) && !TARGET_FLOAT128_HW))
-    ;
-  else if (cond_code == NE
-          || cond_code == GE || cond_code == LE
-          || cond_code == GEU || cond_code == LEU
-          || cond_code == ORDERED || cond_code == UNGE || cond_code == UNLE)
+  if (cond_code == NE
+      || cond_code == GE || cond_code == LE
+      || cond_code == GEU || cond_code == LEU
+      || cond_code == ORDERED || cond_code == UNGE || cond_code == UNLE)
     {
       rtx not_result = gen_reg_rtx (CCEQmode);
       rtx not_op, rev_cond_rtx;
@@ -15716,6 +15711,19 @@ rs6000_emit_sCOND (machine_mode mode, rtx operands[])
       emit_insn (gen_rtx_SET (not_result, not_op));
       condition_rtx = gen_rtx_EQ (VOIDmode, not_result, const0_rtx);
     }
+  return condition_rtx;
+}
+
+void
+rs6000_emit_sCOND (machine_mode mode, rtx operands[])
+{
+  rtx condition_rtx = rs6000_generate_compare (operands[1], mode);
+
+  if (FLOAT_MODE_P (mode) && HONOR_NANS (mode)
+      && !(FLOAT128_VECTOR_P (mode) && !TARGET_FLOAT128_HW))
+  ;
+  else
+    condition_rtx = rs6000_reverse_compare (condition_rtx);

   machine_mode op_mode = GET_MODE (XEXP (operands[1], 0));
   if (op_mode == VOIDmode)