cmd/compile: multiple "internal compiler error" issues

[dmitshur]

There have been a number of "internal compiler error" issues reported recently, each covering specific edge cases that were uncovered. This is an umbrella issue to make it easier to track them.

CC @golang/compiler.

[gabyhelp]

Related Issues

• cmd/compile: fuzzing triggers various crashes or internal compiler errors on tip #49019
• gccgo: internal compiler errors #1557 (closed)
• gccgo: internal compiler errors #1532 (closed)
• gccgo: new internal compilers errors #2661 (closed)
• gccgo: internal compiler errors #1575 (closed)
• cmd/compile internal compiler error after parse error #14006 (closed)
• gccgo: internal compiler errors #1521 (closed)
• cmd/compile: internal compiler error: bad live variable at entry of ... #78134 (closed)
• Internal compiler error with complex operations #33458 (closed)
• cmd/compile: internal compiler error: invalid memory address or nil pointer dereference #51232 (closed)

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