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gallivm: don't use vector selects with llvm 3.7

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llvm 3.7 sometimes simply miscompiles vector selects.
See https://bugs.freedesktop.org/show_bug.cgi?id=94972

This was fixed in llvm r249669
(https://llvm.org/bugs/show_bug.cgi?id=24532).

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
This commit is contained in:
Roland Scheidegger 2016-04-16 23:26:46 +02:00
parent b3616f1326
commit d11111a551
1 changed files with 5 additions and 3 deletions
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8
src/gallium/auxiliary/gallivm/lp_bld_logic.c
View file

@ -315,14 +315,16 @@ lp_build_select(struct lp_build_context *bld,
mask = LLVMBuildTrunc(builder, mask, LLVMInt1TypeInContext(lc), "");
res = LLVMBuildSelect(builder, mask, a, b, "");
}
else if (LLVMIsConstant(mask) ||
LLVMGetInstructionOpcode(mask) == LLVMSExt) {
else if (!(HAVE_LLVM == 0x0307) &&
(LLVMIsConstant(mask) ||
LLVMGetInstructionOpcode(mask) == LLVMSExt)) {
/* Generate a vector select.
*
* Using vector selects should avoid emitting intrinsics hence avoid
* hidering optimization passes, but vector selects weren't properly
* hindering optimization passes, but vector selects weren't properly
* supported yet for a long time, and LLVM will generate poor code when
* the mask is not the result of a comparison.
* Also, llvm 3.7 may miscompile them (bug 94972).
*/
/* Convert the mask to a vector of booleans.