[Git][cmucl/cmucl][issue-435-add-core-math-lisp-support] Address review comments

4 Mar 2026


      Raymond Toy pushed to branch issue-435-add-core-math-lisp-support at cmucl / cmucl


Commits:
06d942be by Raymond Toy at 2026-03-03T19:26:00-08:00
Address review comments

Update exports.lisp.

Add new file openlibm/e_log2f.c to get the function log2f and use it
in irrat.c.  This requires updating Config.x86_common too.

- - - - -


4 changed files:

- src/code/exports.lisp
- src/lisp/Config.x86_common
- src/lisp/irrat.c
- + src/lisp/openlibm/e_log2f.c


Changes:

=====================================
src/code/exports.lisp
=====================================
@@ -2190,7 +2190,30 @@
 	   "STANDARD-PPRINT-DISPATCH-TABLE-MODIFIED-ERROR"
 
 	   "%IEEE754-REM-PI/2"
-	   "%SINCOS")
+	   "%SINCOS"
+	   ;; Single-float functions
+	   "%ACOSF"
+	   "%ACOSHF"
+	   "%ASINF"
+	   "%ASINHF"
+	   "%ATAN2F"
+	   "%ATANF"
+	   "%ATANHF"
+	   "%COSF"
+	   "%COSHF"
+	   "%EXPF"
+	   "%EXPM1F"
+	   "%HYPOTF"
+	   "%LOG10F"
+	   "%LOG1PF"
+	   "%LOG2F"
+	   "%LOGF"
+	   "%POWF"
+	   "%SINF"
+	   "%SINHF"
+	   "%TANF"
+	   "%TANHF"
+	   )
   #+heap-overflow-check
   (:export "DYNAMIC-SPACE-OVERFLOW-WARNING-HIT"
 	   "DYNAMIC-SPACE-OVERFLOW-ERROR-HIT"
@@ -2227,30 +2250,7 @@
 	   "DD-PI"
 	   "INVALID-CASE")
   #+random-xoroshiro
-  (:export "RANDOM-STATE-JUMP")
-  ;; Single-float functions
-  (:export "%ACOSF"
-	   "%ACOSHF"
-	   "%ASINF"
-	   "%ASINHF"
-	   "%ATAN2F"
-	   "%ATANF"
-	   "%ATANHF"
-	   "%COSF"
-	   "%COSHF"
-	   "%EXPF"
-	   "%EXPM1F"
-	   "%HYPOTF"
-	   "%LOG10F"
-	   "%LOG1PF"
-	   "%LOG2F"
-	   "%LOGF"
-	   "%POWF"
-	   "%SINF"
-	   "%SINHF"
-	   "%TANF"
-	   "%TANHF"
-	   ))
+  (:export "RANDOM-STATE-JUMP"))
 
 (dolist
     (name


=====================================
src/lisp/Config.x86_common
=====================================
@@ -110,6 +110,7 @@ OPENLIBM_SRCS = \
 	$(OPENLIBM_DIR)/e_hypotf.c \
 	$(OPENLIBM_DIR)/e_log10f.c \
 	$(OPENLIBM_DIR)/e_logf.c \
+	$(OPENLIBM_DIR)/e_log2f.c \
 	$(OPENLIBM_DIR)/e_powf.c \
 	$(OPENLIBM_DIR)/e_rem_pio2f.c \
 	$(OPENLIBM_DIR)/e_sinhf.c \


=====================================
src/lisp/irrat.c
=====================================
@@ -596,6 +596,6 @@ lisp_log2f(float x)
 #ifdef FEATURE_CORE_MATH
     return cr_log2f(x);
 #else
-    return (float) fdlibm_log2((double) x);
+    return log2f(x);
 #endif
 }


=====================================
src/lisp/openlibm/e_log2f.c
=====================================
@@ -0,0 +1,85 @@
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "cdefs-compat.h"
+//__FBSDID("$FreeBSD: src/lib/msun/src/e_log2f.c,v 1.5 2011/10/15 05:23:28 das Exp $");
+
+/*
+ * Float version of e_log2.c.  See the latter for most comments.
+ */
+
+#include <openlibm_math.h>
+
+#include "math_private.h"
+#include "k_logf.h"
+
+// VBS
+#define float_t float
+
+static const float
+two25      =  3.3554432000e+07, /* 0x4c000000 */
+ivln2hi    =  1.4428710938e+00, /* 0x3fb8b000 */
+ivln2lo    = -1.7605285393e-04; /* 0xb9389ad4 */
+
+static const float zero   =  0.0;
+
+OLM_DLLEXPORT float
+__ieee754_log2f(float x)
+{
+	float f,hfsq,hi,lo,r,y;
+	int32_t i,k,hx;
+
+	GET_FLOAT_WORD(hx,x);
+
+	k=0;
+	if (hx < 0x00800000) {			/* x < 2**-126  */
+	    if ((hx&0x7fffffff)==0)
+		return -two25/zero;		/* log(+-0)=-inf */
+	    if (hx<0) return (x-x)/zero;	/* log(-#) = NaN */
+	    k -= 25; x *= two25; /* subnormal number, scale up x */
+	    GET_FLOAT_WORD(hx,x);
+	}
+	if (hx >= 0x7f800000) return x+x;
+	if (hx == 0x3f800000)
+	    return zero;			/* log(1) = +0 */
+	k += (hx>>23)-127;
+	hx &= 0x007fffff;
+	i = (hx+(0x4afb0d))&0x800000;
+	SET_FLOAT_WORD(x,hx|(i^0x3f800000));	/* normalize x or x/2 */
+	k += (i>>23);
+	y = (float)k;
+	f = x - (float)1.0;
+	hfsq = (float)0.5*f*f;
+	r = k_log1pf(f);
+
+	/*
+	 * We no longer need to avoid falling into the multi-precision
+	 * calculations due to compiler bugs breaking Dekker's theorem.
+	 * Keep avoiding this as an optimization.  See e_log2.c for more
+	 * details (some details are here only because the optimization
+	 * is not yet available in double precision).
+	 *
+	 * Another compiler bug turned up.  With gcc on i386,
+	 * (ivln2lo + ivln2hi) would be evaluated in float precision
+	 * despite runtime evaluations using double precision.  So we
+	 * must cast one of its terms to float_t.  This makes the whole
+	 * expression have type float_t, so return is forced to waste
+	 * time clobbering its extra precision.
+	 */
+	if (sizeof(float_t) > sizeof(float))
+		return (r - hfsq + f) * ((float_t)ivln2lo + ivln2hi) + y;
+
+	hi = f - hfsq;
+	GET_FLOAT_WORD(hx,hi);
+	SET_FLOAT_WORD(hi,hx&0xfffff000);
+	lo = (f - hi) - hfsq + r;
+	return (lo+hi)*ivln2lo + lo*ivln2hi + hi*ivln2hi + y;
+}



View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/06d942be90150dd2ab2a003a...

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View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/06d942be90150dd2ab2a003a...
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Raymond Toy (＠rtoy)

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