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[release-branch.go1.15] cmd/internal/obj/ppc64: don't remove NOP in assembler

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Previously, the assembler removed NOPs from the Prog list in
obj9.go. NOPs shouldn't be removed if they were added as
an inline mark, as described in the issue below.

Fixes #40767

Once the NOPs were left in the Prog list, some instructions
were flagged as invalid because they had an operand which was
not represented in optab. In order to preserve the previous
assembler behavior, entries were added to optab for those
operand cases. They were not flagged as errors before because
the NOP instructions were removed before the code to check the
valid opcode/operand combinations.

Change-Id: Iae5145f94459027cf458e914d7c5d6089807ccf8
Reviewed-on: https://go-review.googlesource.com/c/go/+/247842
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Paul Murphy <murp@ibm.com>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
Reviewed-by: Keith Randall <khr@golang.org>
(cherry picked from commit 7d7bd5abc7)
Reviewed-on: https://go-review.googlesource.com/c/go/+/248381
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
This commit is contained in:
Lynn Boger 2020-08-11 12:04:25 -04:00 committed by Dmitri Shuralyov
parent 33e86004f1
commit a5fb3b1f3d
2 changed files with 6 additions and 8 deletions
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3
src/cmd/internal/obj/ppc64/asm9.go
View File

@ -613,6 +613,9 @@ var optab = []Optab{
{obj.APCDATA, C_LCON, C_NONE, C_NONE, C_LCON, 0, 0, 0},
{obj.AFUNCDATA, C_SCON, C_NONE, C_NONE, C_ADDR, 0, 0, 0},
{obj.ANOP, C_NONE, C_NONE, C_NONE, C_NONE, 0, 0, 0},
{obj.ANOP, C_LCON, C_NONE, C_NONE, C_NONE, 0, 0, 0}, // NOP operand variations added for #40689
{obj.ANOP, C_REG, C_NONE, C_NONE, C_NONE, 0, 0, 0}, // to preserve previous behavior
{obj.ANOP, C_FREG, C_NONE, C_NONE, C_NONE, 0, 0, 0},
{obj.ADUFFZERO, C_NONE, C_NONE, C_NONE, C_LBRA, 11, 4, 0}, // same as ABR/ABL
{obj.ADUFFCOPY, C_NONE, C_NONE, C_NONE, C_LBRA, 11, 4, 0}, // same as ABR/ABL
{obj.APCALIGN, C_LCON, C_NONE, C_NONE, C_NONE, 0, 0, 0}, // align code

11
src/cmd/internal/obj/ppc64/obj9.go
View File

@ -427,7 +427,6 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
/*
* find leaf subroutines
* strip NOPs
* expand RET
* expand BECOME pseudo
*/
@ -557,10 +556,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
q = p
q1 = p.Pcond
if q1 != nil {
for q1.As == obj.ANOP {
q1 = q1.Link
p.Pcond = q1
}
// NOPs are not removed due to #40689.
if q1.Mark&LEAF == 0 {
q1.Mark |= LABEL
@ -587,9 +583,8 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
continue
case obj.ANOP:
q1 = p.Link
q.Link = q1 /* q is non-nop */
q1.Mark |= p.Mark
// NOPs are not removed due to
// #40689
continue
default: