go/ir: fix miscompilation of <<= and >>= statements

dominikh · dominikh · commit 3e57c5dca34d · 2024-02-22T13:50:59.000+01:00
diff --git a/go/ir/UPSTREAM b/go/ir/UPSTREAM
@@ -5,5 +5,5 @@ The changes are too many to list here, and it is best to consider this package i
 Upstream changes still get applied when they address bugs in portions of code we have inherited.
 
 The last upstream commit we've looked at was:
-b900e8804030b22a099f187ef7bdc65bed470c7f
+e854e0228e2ef1cc6e42bbfde1951925096a1272
 
diff --git a/go/ir/builder.go b/go/ir/builder.go
@@ -1027,8 +1027,7 @@ func (b *builder) setCall(fn *Function, e *ast.CallExpr, c *CallCommon) {
 
 // assignOp emits to fn code to perform loc <op>= val.
 func (b *builder) assignOp(fn *Function, loc lvalue, val Value, op token.Token, source ast.Node) {
-	oldv := loc.load(fn, source)
-	loc.store(fn, emitArith(fn, op, oldv, emitConv(fn, val, oldv.Type(), source), loc.typ(), source), source)
+	loc.store(fn, emitArith(fn, op, loc.load(fn, source), val, loc.typ(), source), source)
 }
 
 // localValueSpec emits to fn code to define all of the vars in the

Original file line number	Diff line number	Diff line change
`@@ -1027,8 +1027,7 @@ func (b builder) setCall(fn Function, e ast.CallExpr, c CallCommon) {`
`1027`	`1027`
`1028`	`1028`	`// assignOp emits to fn code to perform loc <op>= val.`
`1029`	`1029`	`func (b builder) assignOp(fn Function, loc lvalue, val Value, op token.Token, source ast.Node) {`
`1030`		`- oldv := loc.load(fn, source)`
`1031`		`- loc.store(fn, emitArith(fn, op, oldv, emitConv(fn, val, oldv.Type(), source), loc.typ(), source), source)`
	`1030`	`+ loc.store(fn, emitArith(fn, op, loc.load(fn, source), val, loc.typ(), source), source)`
`1032`	`1031`	`}`
`1033`	`1032`
`1034`	`1033`	`// localValueSpec emits to fn code to define all of the vars in the`