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ac: fix fast division 

This stopped working with LLVM 11 and might occasionally have been broken
on older LLVM, because the metadata was set on the mul, not on the rcp.

Cc: 19.3 20.0 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4268>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4268>
This commit is contained in:
Marek Olšák 2020-03-20 16:35:45 -04:00 committed by Marge Bot
parent 55b0a676fd
commit 303842b2db
1 changed files with 4 additions and 5 deletions
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9
src/amd/llvm/ac_llvm_build.c
View File

@ -715,12 +715,11 @@ ac_build_fdiv(struct ac_llvm_context *ctx,
*/
LLVMValueRef one = LLVMConstReal(LLVMTypeOf(num), 1.0);
LLVMValueRef rcp = LLVMBuildFDiv(ctx->builder, one, den, "");
LLVMValueRef ret = LLVMBuildFMul(ctx->builder, num, rcp, "");
/* Use v_rcp_f32 instead of precise division. */
if (!LLVMIsConstant(ret))
LLVMSetMetadata(ret, ctx->fpmath_md_kind, ctx->fpmath_md_2p5_ulp);
return ret;
if (!LLVMIsConstant(rcp))
LLVMSetMetadata(rcp, ctx->fpmath_md_kind, ctx->fpmath_md_2p5_ulp);
return LLVMBuildFMul(ctx->builder, num, rcp, "");
}
/* See fast_idiv_by_const.h. */