[go] cmd/compile: avoid rewriting switch case expressions in b.Loop
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Chencheng Jiang (Gerrit)
Aug 9, 2026, 5:04:55 PM (13 hours ago) Aug 9
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Chencheng Jiang has uploaded the change for review![]( "Open in Gerrit")
Commit message
cmd/compile: avoid rewriting switch case expressions in b.Loop
CaseClause.List contains expressions, but the bloop pass treats it as a
list of statements. When a case expression is a function call, the pass
replaces it with a block containing an assignment and a KeepAlive call.
Escape analysis then panics because the block has no expression type.
Only preserve statements in the case body. Case expressions are already
used by the switch and do not need additional keep-alive instrumentation.
Add a regression test for a function call used as a case expression.
Fixes #80801
Change-Id: Id8c1e83ab54339885445fd7a45348410ad4631cb
Change diff
diff --git a/src/cmd/compile/internal/bloop/bloop.go b/src/cmd/compile/internal/bloop/bloop.go
index d5f001a..abb6838 100644
--- a/src/cmd/compile/internal/bloop/bloop.go
+++ b/src/cmd/compile/internal/bloop/bloop.go
@@ -325,7 +325,6 @@
case *ir.BlockStmt:
preserveStmts(e.curFn, n.List)
case *ir.CaseClause:
- preserveStmts(e.curFn, n.List)
preserveStmts(e.curFn, n.Body)
case *ir.CommClause:
preserveStmts(e.curFn, n.Body)
diff --git a/test/bloop.go b/test/bloop.go
index d718425..c53a17e 100644
--- a/test/bloop.go
+++ b/test/bloop.go
@@ -56,6 +56,10 @@
case 2:
caninline(1) // ERROR "inlining call to caninline" "function result will be kept alive"
}
+ // Case expressions are not statements and should not be rewritten by the bloop pass.
+ switch cond {
+ case caninline(2): // ERROR "inlining call to caninline"
+ }
{
caninline(1) // ERROR "inlining call to caninline" "function result will be kept alive"
}
Change information
Files:
- M src/cmd/compile/internal/bloop/bloop.go
- M test/bloop.go
Change size: XS
Delta: 2 files changed, 4 insertions(+), 1 deletion(-)
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Youlin Feng (Gerrit)
12:32 AM (5 hours ago) 12:32 AM
to Chencheng Jiang, goph...@pubsubhelper.golang.org, Robert Griesemer, Keith Randall, Martin Möhrmann, Gopher Robot, golang-co...@googlegroups.com
Attention needed from Chencheng Jiang and Keith Randall
Youlin Feng voted Commit-Queue+1![]( "Open in Gerrit")
| Commit-Queue | +1 |
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