[go] cmd/compile: correct OffPtr collapsing rule type

[Junyang Shao (Gerrit)]

Junyang Shao has uploaded the change for review

Commit message

cmd/compile: correct OffPtr collapsing rule type

It looks like the current way OffPtr is collapsed takes the type of the
first value in the chain, but it should really be the last one in the
chain.

Change-Id: I168804d05f0eb873b1558f76190be03947ad32dc

Change diff

diff --git a/src/cmd/compile/internal/ssa/_gen/generic.rules b/src/cmd/compile/internal/ssa/_gen/generic.rules
index b16aa47..4058906 100644
--- a/src/cmd/compile/internal/ssa/_gen/generic.rules
+++ b/src/cmd/compile/internal/ssa/_gen/generic.rules
@@ -904,7 +904,7 @@
 	=> mem
 
 // Collapse OffPtr
-(OffPtr (OffPtr p [y]) [x]) => (OffPtr p [x+y])
+(OffPtr (OffPtr <t> p [y]) [x]) => (OffPtr <t> p [x+y])
 (OffPtr p [0]) && v.Type.Compare(p.Type) == types.CMPeq => p
 
 // indexing operations
diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 5e0135b..c7421cd 100644
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -21821,16 +21821,18 @@
 }
 func rewriteValuegeneric_OpOffPtr(v *Value) bool {
 	v_0 := v.Args[0]
-	// match: (OffPtr (OffPtr p [y]) [x])
-	// result: (OffPtr p [x+y])
+	// match: (OffPtr (OffPtr <t> p [y]) [x])
+	// result: (OffPtr <t> p [x+y])
 	for {
 		x := auxIntToInt64(v.AuxInt)
 		if v_0.Op != OpOffPtr {
 			break
 		}
+		t := v_0.Type
 		y := auxIntToInt64(v_0.AuxInt)
 		p := v_0.Args[0]
 		v.reset(OpOffPtr)
+		v.Type = t
 		v.AuxInt = int64ToAuxInt(x + y)
 		v.AddArg(p)
 		return true

Change information

Files:

• M src/cmd/compile/internal/ssa/_gen/generic.rules
• M src/cmd/compile/internal/ssa/rewritegeneric.go

Change size: XS

Delta: 2 files changed, 5 insertions(+), 3 deletions(-)

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Gerrit-Project: go

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Gerrit-Change-Id: I168804d05f0eb873b1558f76190be03947ad32dc

Gerrit-Change-Number: 708297

Gerrit-PatchSet: 1

Gerrit-Owner: Junyang Shao <shaoj...@google.com>

[Junyang Shao (Gerrit)]

Attention needed from David Chase and Keith Randall

Junyang Shao voted Commit-Queue+1

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+1

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Gerrit-Owner: Junyang Shao <shaoj...@google.com>

Gerrit-Reviewer: David Chase <drc...@google.com>

Gerrit-Reviewer: Junyang Shao <shaoj...@google.com>

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Gerrit-Comment-Date: Wed, 01 Oct 2025 16:25:41 +0000

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