cmd/internal/gc: use 512 bits (rather than 464) for multi-precision arithmetic
The original implementation used 16 int "words" but only 29 bits per word
for a total of 16*29 = 464 bits, with a space consumption of 16*64 = 1024
bits on a 64 bit machine. Switching to 512 bits increases precision while
still using (in the worst case) half the amount of memory per mp value on
a 64 bit machine.
Also: Decreased permitted number of least-significant mantissa bits which
may be incorrect when considering if a precise floating-point constant is
an integer from 29 to 16 bits.
Change-Id: Iee9287056f0e9aa4f06ceac0724ff4674f710c53
Reviewed-on: https://go-review.googlesource.com/8429
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/test/fixedbugs/issue7740.go b/test/fixedbugs/issue7740.go
index d5005ed..8f1afe8 100644
--- a/test/fixedbugs/issue7740.go
+++ b/test/fixedbugs/issue7740.go
@@ -21,7 +21,7 @@
var prec float64
switch runtime.Compiler {
case "gc":
- prec = 16 * 29
+ prec = 512
case "gccgo":
prec = 256
default:
