0e1afa3eba
A bare `return X;` / `raise` in the middle of a block closed the current
LLVM basic block, but lowerBlock / lowerBlockValue only stopped the
statement loop on the `block_terminated` flag — which lowerReturn
deliberately never sets (it would leak past an `if cond { return }` merge
block). So trailing dead statements were emitted into the already-closed
block, tripping the LLVM verifier with "Terminator found in the middle of
a basic block".
Fix: also stop the statement loop when currentBlockHasTerminator() is
true. That is CFG-level termination of the *current* block, which is
naturally false at an if / inline-if merge block, so conditional returns
still fall through to their trailing statements.
This unblocks ERR E5.1: the canonical failable-closure form
`closure((x) -> (s32,!) { raise error.X; return x; })` has a dead
`return x;` after the unconditional raise and tripped the verifier.
Regression: examples/0038-basic-dead-code-after-terminator.sx.
35 lines
1.5 KiB
Plaintext
35 lines
1.5 KiB
Plaintext
// Dead statements after a block-terminating statement (`return` / `raise`) are
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// dropped instead of being emitted into the already-closed basic block.
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// Regression (issue 0061): a bare `return X;` / `raise` mid-block closed the
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// LLVM basic block but lowering kept emitting the trailing statements into it
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// → "Terminator found in the middle of a basic block". The canonical failable
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// closure form `{ raise error.X; return x; }` tripped this, blocking ERR E5.1.
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//
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// The fix must NOT over-reach: a CONDITIONAL `if cond { return }` (and the
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// `inline if` pack form) leaves a fresh merge block, so its trailing statements
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// must still run — exercised by `clamp` / `pick` below.
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#import "modules/std.sx";
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E :: error { Neg }
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// dead `return 99;` after an unconditional return
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const_one :: () -> s64 { return 1; return 99; }
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// dead `return x;` after an unconditional raise (the failable closure shape)
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always_raise :: (x: s64) -> (s64, !E) { raise error.Neg; return x; }
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// guard: a conditional return must still fall through to the trailing return
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clamp :: (x: s64) -> s64 { if x > 10 { return 10; } return x; }
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main :: () -> s32 {
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print("const_one={}\n", const_one()); // 1
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print("raised={}\n", always_raise(5) catch e 0); // 0
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print("clamp_hi={}\n", clamp(42)); // 10
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print("clamp_lo={}\n", clamp(7)); // 7
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// dead code after a `return` at main's own block level is dropped.
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return 0;
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print("unreachable\n");
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}
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