runtime: delete timediv

Now that the compiler handles constant 64-bit divisions
without function calls on 32-bit systems, we no longer need
to maintain and test a bad custom implementation of 64-bit division.

Change-Id: If28807ad4f86507267ae69bc8f0b09ec18e98b66
Reviewed-on: https://go-review.googlesource.com/c/go/+/716463
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

1 files changed, 0 insertions, 33 deletions

diff --git a/src/runtime/runtime1.go b/src/runtime/runtime1.go
index 3ec5c44ebd..43e4c14236 100644
--- a/src/runtime/runtime1.go
+++ b/src/runtime/runtime1.go
@@ -212,10 +212,6 @@ func check() {
 		throw("bad unsafe.Sizeof y1")
 	}
 
-	if timediv(12345*1000000000+54321, 1000000000, &e) != 12345 || e != 54321 {
-		throw("bad timediv")
-	}
-
 	var z uint32
 	z = 1
 	if !atomic.Cas(&z, 1, 2) {
@@ -593,35 +589,6 @@ func setTraceback(level string) {
 	atomic.Store(&traceback_cache, t)
 }
 
-// Poor mans 64-bit division.
-// This is a very special function, do not use it if you are not sure what you are doing.
-// int64 division is lowered into _divv() call on 386, which does not fit into nosplit functions.
-// Handles overflow in a time-specific manner.
-// This keeps us within no-split stack limits on 32-bit processors.
-//
-//go:nosplit
-func timediv(v int64, div int32, rem *int32) int32 {
-	res := int32(0)
-	for bit := 30; bit >= 0; bit-- {
-		if v >= int64(div)<<uint(bit) {
-			v = v - (int64(div) << uint(bit))
-			// Before this for loop, res was 0, thus all these
-			// power of 2 increments are now just bitsets.
-			res |= 1 << uint(bit)
-		}
-	}
-	if v >= int64(div) {
-		if rem != nil {
-			*rem = 0
-		}
-		return 0x7fffffff
-	}
-	if rem != nil {
-		*rem = int32(v)
-	}
-	return res
-}
-
 // Helpers for Go. Must be NOSPLIT, must only call NOSPLIT functions, and must not block.
 
 //go:nosplit