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Fix jit compilation bug on wide tables.

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The function generated to perform JIT compiled tuple deforming failed
when HeapTupleHeader's t_hoff was bigger than a signed int8. I'd
failed to realize that LLVM's getelementptr would treat an int8 index
argument as signed, rather than unsigned.  That means that a hoff
larger than 127 would result in a negative offset being applied.  Fix
that by widening the index to 32bit.

Add a testcase with a wide table. Don't drop it, as it seems useful to
verify other tools deal properly with wide tables.

Thanks to Justin Pryzby for both reporting a bug and then reducing it
to a reproducible testcase!

Reported-By: Justin Pryzby
Author: Andres Freund
Discussion: https://postgr.es/m/20181115223959.GB10913@telsasoft.com
Backpatch: 11, just as jit compilation was
This commit is contained in:
Andres Freund
2018-11-27 10:07:03 -08:00
parent f17889b221
commit b238527664
4 changed files with 30 additions and 3 deletions
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12
src/backend/jit/llvm/llvmjit_deform.c
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@ -248,10 +248,16 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc,
v_infomask2,
"maxatt");
/*
* Need to zext, as getelementptr otherwise treats hoff as a signed 8bit
* integer, which'd yield a negative offset for t_hoff > 127.
*/
v_hoff =
l_load_struct_gep(b, v_tuplep,
FIELDNO_HEAPTUPLEHEADERDATA_HOFF,
"t_hoff");
LLVMBuildZExt(b,
l_load_struct_gep(b, v_tuplep,
FIELDNO_HEAPTUPLEHEADERDATA_HOFF,
""),
LLVMInt32Type(), "t_hoff");
v_tupdata_base =
LLVMBuildGEP(b,