math/big: temporarily disable buggy shlVU assembly for arm64

This addresses the failures we have seen in #31084. The correct
fix is to find the actual bug in the assembly code.

Updates #31084.

Change-Id: I437780c53d0c4423d742e2e3b650b899ce845372
Reviewed-on: https://go-review.googlesource.com/c/go/+/169721
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/math/big/arith_arm64.s b/src/math/big/arith_arm64.s
index eebdf59fb2a314df08092064ee5b2607d4901793..bb23751ba3b9b44a6fbcfac01491413eead469d1 100644 (file)
--- a/src/math/big/arith_arm64.s
+++ b/src/math/big/arith_arm64.s
@@ -197,6 +197,10 @@ len0:
 
 // func shlVU(z, x []Word, s uint) (c Word)
 TEXT ·shlVU(SB),NOSPLIT,$0
+       // Disable assembly for now - it is subtly incorrect.
+       // See #31084 for a test that fails using this code.
+       B       ·shlVU_g(SB)
+
        MOVD    z+0(FP), R0
        MOVD    z_len+8(FP), R1
        MOVD    x+24(FP), R2