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| author | Keith Randall <khr@golang.org> | 2022-06-29 13:22:59 -0700 |
|---|---|---|
| committer | Cherry Mui <cherryyz@google.com> | 2022-07-25 23:15:10 +0000 |
| commit | 489c1485780f6326fb5f446bd9d97dff2ff0abcf (patch) | |
| tree | 95a9e2ffdd04c3bb07f60b152ac60ccc9258ffae /src | |
| parent | 66c60f076c167f252b0d8f0ac37f4c5c0c2adb51 (diff) | |
| download | go-489c1485780f6326fb5f446bd9d97dff2ff0abcf.tar.gz go-489c1485780f6326fb5f446bd9d97dff2ff0abcf.zip | |
[release-branch.go1.17] cmd/compile: fix prove pass when upper condition is <= maxint
When the terminating condition is <= X, we need to make sure that
X+step doesn't overflow.
Fixes #53617
Change-Id: I36e5384d05b4d7168e48db6094200fcae409bfe5
Reviewed-on: https://go-review.googlesource.com/c/go/+/415219
Reviewed-by: Than McIntosh <thanm@google.com>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
(cherry picked from commit 31b8c23c5702f129aca9241bbb2132c90b1929cc)
Reviewed-on: https://go-review.googlesource.com/c/go/+/415415
Reviewed-by: Keith Randall <khr@google.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/ssa/loopbce.go | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/loopbce.go b/src/cmd/compile/internal/ssa/loopbce.go index 5a4bc1d60a..fd03efb417 100644 --- a/src/cmd/compile/internal/ssa/loopbce.go +++ b/src/cmd/compile/internal/ssa/loopbce.go @@ -159,6 +159,13 @@ func findIndVar(f *Func) []indVar { step = -step } + if flags&indVarMaxInc != 0 && max.Op == OpConst64 && max.AuxInt+step < max.AuxInt { + // For a <= comparison, we need to make sure that a value equal to + // max can be incremented without overflowing. + // (For a < comparison, the %step check below ensures no overflow.) + continue + } + // Up to now we extracted the induction variable (ind), // the increment delta (inc), the temporary sum (nxt), // the mininum value (min) and the maximum value (max). |