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ac/nir: add a workaround for bitfield_extract when count is 0 

LLVM 7 returns incorrect results when count is 0, something
has been broken since LLVM 6. Of course, the best solution is
to fix LLVM but this workaround works as expected for now.

Original workaround by Philippe Rebohle.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107276
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
This commit is contained in:
Samuel Pitoiset 2018-07-19 20:27:11 +02:00
parent e2e32b6afd
commit 3d41757788
1 changed files with 17 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/amd/common/ac_nir_to_llvm.c
View File

@ -418,10 +418,24 @@ static LLVMValueRef emit_bitfield_extract(struct ac_llvm_context *ctx,
const LLVMValueRef srcs[3])
{
LLVMValueRef result;
LLVMValueRef icond = LLVMBuildICmp(ctx->builder, LLVMIntEQ, srcs[2], LLVMConstInt(ctx->i32, 32, false), "");
result = ac_build_bfe(ctx, srcs[0], srcs[1], srcs[2], is_signed);
result = LLVMBuildSelect(ctx->builder, icond, srcs[0], result, "");
if (HAVE_LLVM < 0x0700) {
LLVMValueRef icond = LLVMBuildICmp(ctx->builder, LLVMIntEQ, srcs[2], LLVMConstInt(ctx->i32, 32, false), "");
result = ac_build_bfe(ctx, srcs[0], srcs[1], srcs[2], is_signed);
result = LLVMBuildSelect(ctx->builder, icond, srcs[0], result, "");
} else {
/* FIXME: LLVM 7 returns incorrect result when count is 0.
* https://bugs.freedesktop.org/show_bug.cgi?id=107276
*/
LLVMValueRef zero = LLVMConstInt(ctx->i32, 0, false);
LLVMValueRef icond1 = LLVMBuildICmp(ctx->builder, LLVMIntEQ, srcs[2], LLVMConstInt(ctx->i32, 32, false), "");
LLVMValueRef icond2 = LLVMBuildICmp(ctx->builder, LLVMIntEQ, srcs[2], zero, "");
result = ac_build_bfe(ctx, srcs[0], srcs[1], srcs[2], is_signed);
result = LLVMBuildSelect(ctx->builder, icond1, srcs[0], result, "");
result = LLVMBuildSelect(ctx->builder, icond2, zero, result, "");
}
return result;
}