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| author | Andres Freund <andres@anarazel.de> | 2018-11-27 10:07:03 -0800 |
|---|---|---|
| committer | Andres Freund <andres@anarazel.de> | 2018-11-27 10:07:03 -0800 |
| commit | b238527664ec6f6c9d00dba4cc2f3dab1c8b8b04 (patch) | |
| tree | 03df0a6229aadc8a458ef673eec64ddd1ee1e64b /src/backend/jit/llvm/llvmjit_deform.c | |
| parent | f17889b2214194d7bd33900509bf08959d5a7efa (diff) | |
| download | postgresql-b238527664ec6f6c9d00dba4cc2f3dab1c8b8b04.tar.gz postgresql-b238527664ec6f6c9d00dba4cc2f3dab1c8b8b04.zip | |
Fix jit compilation bug on wide tables.
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
Diffstat (limited to 'src/backend/jit/llvm/llvmjit_deform.c')
| -rw-r--r-- | src/backend/jit/llvm/llvmjit_deform.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/src/backend/jit/llvm/llvmjit_deform.c b/src/backend/jit/llvm/llvmjit_deform.c index 4111bf0a54b..d168eae0873 100644 --- a/src/backend/jit/llvm/llvmjit_deform.c +++ b/src/backend/jit/llvm/llvmjit_deform.c @@ -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, |