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cmd/compile: use proved bounds to remove signed division fix-ups

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prove is able to find 94 occurrences in std cmd where a divisor
can't have the value -1. The change removes
the extraneous fix-up code for these cases.

Fixes #25239

Change-Id: Ic184de971f47cc57c702eb72805b8e291c14035d
Reviewed-on: https://go-review.googlesource.com/c/130215
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
ChrisALiles 2018-08-06 19:50:38 +10:00 • committed by Brad Fitzpatrick
parent 47cc59f31f
commit 13d5cd7847
14 changed files with 299 additions and 98 deletions
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15
src/cmd/compile/internal/ssa/gen/genericOps.go
View file

@ -66,23 +66,26 @@ var genericOps = []opData{
{name: "Avg32u", argLength: 2, typ: "UInt32"}, // 32-bit platforms only
{name: "Avg64u", argLength: 2, typ: "UInt64"}, // 64-bit platforms only
// For Div16, Div32 and Div64, AuxInt non-zero means that the divisor has been proved to be not -1
// or that the dividend is not the most negative value.
{name: "Div8", argLength: 2}, // arg0 / arg1, signed
{name: "Div8u", argLength: 2}, // arg0 / arg1, unsigned
{name: "Div16", argLength: 2},
{name: "Div16", argLength: 2, aux: "Bool"},
{name: "Div16u", argLength: 2},
{name: "Div32", argLength: 2},
{name: "Div32", argLength: 2, aux: "Bool"},
{name: "Div32u", argLength: 2},
{name: "Div64", argLength: 2},
{name: "Div64", argLength: 2, aux: "Bool"},
{name: "Div64u", argLength: 2},
{name: "Div128u", argLength: 3}, // arg0:arg1 / arg2 (128-bit divided by 64-bit), returns (q, r)
// For Mod16, Mod32 and Mod64, AuxInt non-zero means that the divisor has been proved to be not -1.
{name: "Mod8", argLength: 2}, // arg0 % arg1, signed
{name: "Mod8u", argLength: 2}, // arg0 % arg1, unsigned
{name: "Mod16", argLength: 2},
{name: "Mod16", argLength: 2, aux: "Bool"},
{name: "Mod16u", argLength: 2},
{name: "Mod32", argLength: 2},
{name: "Mod32", argLength: 2, aux: "Bool"},
{name: "Mod32u", argLength: 2},
{name: "Mod64", argLength: 2},
{name: "Mod64", argLength: 2, aux: "Bool"},
{name: "Mod64u", argLength: 2},
{name: "And8", argLength: 2, commutative: true}, // arg0 & arg1