From: Maciej W. Rozycki <macro@linux-mips.org>
Date: Fri, 8 Jan 2021 01:50:10 +0000 (+0000)
Subject: RTL: Update `const_double_zero' handling for mode and callable insns
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=859be2e44aceb3766e4517e827e2aad7c9711b4c;p=gcc.git

RTL: Update `const_double_zero' handling for mode and callable insns

Handle machine mode specification with `const_double_zero' and handle
the rtx with callable code produced from named insns.  Complementing
commit 20ab43b5cad6 ("RTL: Add `const_double_zero' syntactic rtx") and
removing a commit c60d0736dff7 ("PDP11: Use `const_double_zero' to
express double zero constant") build regression observed with the
`pdp11-aout' target:

genemit: Internal error: abort in gen_exp, at genemit.c:202
make[2]: *** [Makefile:2427: s-emit] Error 1

where a:

(const_double 0 [0] 0 [0] 0 [0] 0 [0])

rtx coming from:

(parallel [
        (set (reg:CC 16)
            (compare:CC (abs:DF (match_operand:DF 1 ("general_operand") ("0,0")))
                (const_double 0 [0] 0 [0] 0 [0] 0 [0])))
        (set (match_operand:DF 0 ("nonimmediate_operand") ("=fR,Q"))
            (abs:DF (match_dup 1)))
    ])

and ultimately `(const_double_zero)' referred in a named RTL insn cannot
be interpreted.  Handle the rtx then by supplying the constant 0 double
operand requested, resulting in the following update to insn-emit.c code
produced for the `pdp11-aout' target, relative to before the triggering
commit:

@@ -1514,7 +1514,7 @@ gen_absdf2_cc (rtx operand0 ATTRIBUTE_UN
 	gen_rtx_COMPARE (CCmode,
 	gen_rtx_ABS (DFmode,
 	operand1),
-	const0_rtx)),
+	CONST_DOUBLE_ATOF ("0", VOIDmode))),
 		gen_rtx_SET (operand0,
 	gen_rtx_ABS (DFmode,
 	copy_rtx (operand1)))));
@@ -1555,7 +1555,7 @@ gen_negdf2_cc (rtx operand0 ATTRIBUTE_UN
 	gen_rtx_COMPARE (CCmode,
 	gen_rtx_NEG (DFmode,
 	operand1),
-	const0_rtx)),
+	CONST_DOUBLE_ATOF ("0", VOIDmode))),
 		gen_rtx_SET (operand0,
 	gen_rtx_NEG (DFmode,
 	copy_rtx (operand1)))));
@@ -1790,7 +1790,7 @@ gen_muldf3_cc (rtx operand0 ATTRIBUTE_UN
 	gen_rtx_MULT (DFmode,
 	operand1,
 	operand2),
-	const0_rtx)),
+	CONST_DOUBLE_ATOF ("0", VOIDmode))),
 		gen_rtx_SET (operand0,
 	gen_rtx_MULT (DFmode,
 	copy_rtx (operand1),
@@ -1942,7 +1942,7 @@ gen_divdf3_cc (rtx operand0 ATTRIBUTE_UN
 	gen_rtx_DIV (DFmode,
 	operand1,
 	operand2),
-	const0_rtx)),
+	CONST_DOUBLE_ATOF ("0", VOIDmode))),
 		gen_rtx_SET (operand0,
 	gen_rtx_DIV (DFmode,
 	copy_rtx (operand1),

This does not (yet) remove VOIDmode CONST_DOUBLE use, as it is up to
individual machine descriptions to choose.

	gcc/
	* genemit.c (gen_exp) <CONST_DOUBLE>: Handle `const_double_zero'
	rtx.
	* read-rtl.c (rtx_reader::read_rtx_code): Handle machine mode
	with `const_double_zero'.
	* doc/rtl.texi (Constant Expression Types): Document it.
---

diff --git a/gcc/doc/rtl.texi b/gcc/doc/rtl.texi
index 69c481fb7a4..edbc60fdfba 100644
--- a/gcc/doc/rtl.texi
+++ b/gcc/doc/rtl.texi
@@ -1719,13 +1719,13 @@ of code @code{const_double} and therefore a syntactic alias has been
 provided:
 
 @smallexample
-(const_double_zero)
+(const_double_zero:@var{m})
 @end smallexample
 
 standing for:
 
 @smallexample
-(const_double 0 0 @dots{})
+(const_double:@var{m} 0 0 @dots{})
 @end smallexample
 
 for matching the floating-point value zero, possibly the only useful one.
diff --git a/gcc/genemit.c b/gcc/genemit.c
index 3cd6499037d..89d9e990b73 100644
--- a/gcc/genemit.c
+++ b/gcc/genemit.c
@@ -195,6 +195,14 @@ gen_exp (rtx x, enum rtx_code subroutine_type, char *used, md_rtx_info *info)
       return;
 
     case CONST_DOUBLE:
+      /* Handle `const_double_zero' rtx.  */
+      if (CONST_DOUBLE_REAL_VALUE (x)->cl == rvc_zero)
+	{
+	  printf ("CONST_DOUBLE_ATOF (\"0\", %smode)",
+		  GET_MODE_NAME (GET_MODE (x)));
+	  return;
+	}
+      /* Fall through.  */
     case CONST_FIXED:
     case CONST_WIDE_INT:
       /* These shouldn't be written in MD files.  Instead, the appropriate
diff --git a/gcc/read-rtl.c b/gcc/read-rtl.c
index 11e2686262c..925402877ec 100644
--- a/gcc/read-rtl.c
+++ b/gcc/read-rtl.c
@@ -1658,6 +1658,15 @@ rtx_reader::read_rtx_code (const char *code_name)
       return_rtx = rtx_alloc (code);
       memset (return_rtx, 0, RTX_CODE_SIZE (code));
       PUT_CODE (return_rtx, code);
+      c = read_skip_spaces ();
+      if (c == ':')
+	{
+	  file_location loc = read_name (&name);
+	  record_potential_iterator_use (&modes, loc, return_rtx, 0,
+					 name.string);
+	}
+      else
+	unread_char (c);
       return return_rtx;
     }