From 862f66c15b16e4d17b07c58c766ad02069b4d53c Mon Sep 17 00:00:00 2001
From: dgp <dgp@noemail.net>
Date: Tue, 19 Sep 2006 16:31:56 +0000
Subject:         * generic/tclExecute.c (INST_EXPON):    Native type overflow
 detection         * tests/expr.test:      was completely broken.  Falling
 back on use of         bignums for all non-trivial ** calculations until     
    native-type-constrained special cases can be done carefully and        
 correctly.  [Bug 1561260].

FossilOrigin-Name: adcaa18a0d0cb480b3b872222c2cf5c63a4460a2
---
 ChangeLog            |  8 ++++++++
 generic/tclExecute.c | 52 ++++++----------------------------------------------
 tests/expr.test      |  8 +++++++-
 3 files changed, 21 insertions(+), 47 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 28f2dc1..0f4c66d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2006-09-19  Don Porter  <dgp@users.sourceforge.net>
+
+	* generic/tclExecute.c (INST_EXPON):	Native type overflow detection
+	* tests/expr.test:	was completely broken.  Falling back on use of
+	bignums for all non-trivial ** calculations until
+	native-type-constrained special cases can be done carefully and
+	correctly.  [Bug 1561260].
+
 2006-09-15  Jeff Hobbs  <jeffh@ActiveState.com>
 
 	* library/http/http.tcl:      Change " " -> "+" url encoding mapping
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index d664134..7006d00 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -12,7 +12,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclExecute.c,v 1.244 2006/09/11 04:54:11 dgp Exp $
+ * RCS: @(#) $Id: tclExecute.c,v 1.245 2006/09/19 16:31:56 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -4694,7 +4694,7 @@ TclExecuteByteCode(
 
 	/* TODO: Attempts to re-use unshared operands on stack */
 	if (*pc == INST_EXPON) {
-	    long l2 = 0;
+	    long l1, l2 = 0;
 	    int oddExponent = 0, negativeExponent = 0;
 	    if (type2 == TCL_NUMBER_LONG) {
 		l2 = *((CONST long *)ptr2);
@@ -4735,7 +4735,7 @@ TclExecuteByteCode(
 
 	    if (negativeExponent) {
 		if (type1 == TCL_NUMBER_LONG) {
-		    long l1 = *((CONST long *)ptr1);
+		    l1 = *((CONST long *)ptr1);
 		    switch (l1) {
 		    case 0:
 			/* zero to a negative power is div by zero error */
@@ -4762,7 +4762,7 @@ TclExecuteByteCode(
 	    }
 
 	    if (type1 == TCL_NUMBER_LONG) {
-		long l1 = *((CONST long *)ptr1);
+		l1 = *((CONST long *)ptr1);
 		switch (l1) {
 		case 0:
 		    /* zero to a positive power is zero */
@@ -4781,13 +4781,8 @@ TclExecuteByteCode(
 		    NEXT_INST_F(1, 2, 1);
 		}
 	    }
-
-	    if (type2 != TCL_NUMBER_LONG) {
-		result = TCL_ERROR;
-		Tcl_SetObjResult(interp,
-			Tcl_NewStringObj("exponent too large", -1));
-		goto checkForCatch;
-	    }
+	    /* TODO: Perform those computations that fit in native types */
+	    goto overflow;
 	}
 
 	if ((*pc != INST_MULT)
@@ -4846,41 +4841,6 @@ TclExecuteByteCode(
 		    wResult -= 1;
 		}
 		break;
-	    case INST_EXPON: {
-		/* TODO: smarter overflow detection ? */
-		int wasNegative;
-		if (w2 & 1) {
-		    wResult = w1;
-		} else {
-		    wResult = Tcl_LongAsWide(1);
-		}
-		w1 *= w1;
-		w2 /= 2;
-		if (w2 == 0) {
-		    break;
-		}
-		for (; w2>Tcl_LongAsWide(1) ; w1*=w1,w2/=2) {
-		    wasNegative = (wResult < 0);
-		    if (w1 <= 0) {
-			goto overflow;
-		    }
-		    if (w2 & 1) {
-			wResult *= w1;
-			if (wasNegative != (wResult < 0)) {
-			    goto overflow;
-			}
-		    }
-		}
-		wasNegative = (wResult < 0);
-		if (w1 <= 0) {
-		    goto overflow;
-		}
-		wResult *=  w1;
-		if (wasNegative != (wResult < 0)) {
-		    goto overflow;
-		}
-		break;
-	    }
 	    default:
 		/* Unused, here to silence compiler warning. */
 		wResult = 0;
diff --git a/tests/expr.test b/tests/expr.test
index a26dc63..20ab38b 100644
--- a/tests/expr.test
+++ b/tests/expr.test
@@ -10,7 +10,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: expr.test,v 1.60 2006/09/11 04:54:12 dgp Exp $
+# RCS: @(#) $Id: expr.test,v 1.61 2006/09/19 16:31:57 dgp Exp $
 
 if {[lsearch [namespace children] ::tcltest] == -1} {
     package require tcltest 2.1
@@ -974,6 +974,12 @@ test expr-23.42 {INST_EXPON: overflow to big integer} {expr 4**32} [expr 1<<64]
 test expr-23.43 {INST_EXPON: overflow to big integer} {expr 16**16} [expr 1<<64]
 test expr-23.44 {INST_EXPON: overflow to big integer} {expr 256**8} [expr 1<<64]
 test expr-23.45 {INST_EXPON: Bug 1555371} {expr 2**1} 2
+test expr-23.46 {INST_EXPON: Bug 1561260} -body {
+    expr 5**28
+} -match glob -result *5
+test expr-23.47 {INST_EXPON: Bug 1561260} {
+    expr 2**32*5**32
+} 1[string repeat 0 32]
 
 # Some compilers get this wrong; ensure that we work around it correctly
 test expr-24.1 {expr edge cases; shifting} {expr int(5)>>32} 0
-- 
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