Files
ispc/builtins/dispatch.ll
Matt Pharr 371d4be8ef Fix bugs in detection of Ivy Bridge systems.
We were incorrectly characterizing them as basic AVX1 without further
extensions, due to a bug in the logic to check CPU features.
2012-07-12 14:11:15 -07:00

161 lines
6.4 KiB
LLVM

;; Copyright (c) 2011, Intel Corporation
;; All rights reserved.
;;
;; Redistribution and use in source and binary forms, with or without
;; modification, are permitted provided that the following conditions are
;; met:
;;
;; * Redistributions of source code must retain the above copyright
;; notice, this list of conditions and the following disclaimer.
;;
;; * Redistributions in binary form must reproduce the above copyright
;; notice, this list of conditions and the following disclaimer in the
;; documentation and/or other materials provided with the distribution.
;;
;; * Neither the name of Intel Corporation nor the names of its
;; contributors may be used to endorse or promote products derived from
;; this software without specific prior written permission.
;;
;;
;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
;; IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
;; TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
;; PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
;; OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
;; EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
;; PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
;; PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
;; LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;; This file defines various functions that are used when generating the
;; the "dispatch" object/assembly file that has entrypoints for each
;; exported function in a module that dispatch to the best available
;; variant of that function that will run on the system's CPU.
;; Stores the best target ISA that the system on which we're actually
;; running supports. -1 represents "uninitialized", otherwise this value
;; should correspond to one of the enumerant values of Target::ISA from
;; ispc.h.
@__system_best_isa = internal global i32 -1
declare void @abort() noreturn
;; The below is the result of running "clang -O2 -emit-llvm -c -o -" on the
;; following code... Specifically, __get_system_isa should return a value
;; corresponding to one of the Target::ISA enumerant values that gives the
;; most capable ISA that the curremt system can run.
;;
;; Note: clang from LLVM 3.0 should be used if this is updated, for maximum
;; backwards compatibility for anyone building ispc with LLVM 3.0
;;
;; #include <stdint.h>
;; #include <stdlib.h>
;;
;; static void __cpuid(int info[4], int infoType) {
;; __asm__ __volatile__ ("cpuid"
;; : "=a" (info[0]), "=b" (info[1]), "=c" (info[2]), "=d" (info[3])
;; : "0" (infoType));
;; }
;;
;; /* Save %ebx in case it's the PIC register */
;; static void __cpuid_count(int info[4], int level, int count) {
;; __asm__ __volatile__ ("xchg{l}\t{%%}ebx, %1\n\t"
;; "cpuid\n\t"
;; "xchg{l}\t{%%}ebx, %1\n\t"
;; : "=a" (info[0]), "=r" (info[1]), "=c" (info[2]), "=d" (info[3])
;; : "0" (level), "2" (count));
;; }
;;
;; int32_t __get_system_isa() {
;; int info[4];
;; __cpuid(info, 1);
;;
;; /* NOTE: the values returned below must be the same as the
;; corresponding enumerant values in Target::ISA. */
;; if ((info[2] & (1 << 28)) != 0) {
;; if ((info[2] & (1 << 29)) != 0 && // F16C
;; (info[2] & (1 << 30)) != 0) { // RDRAND
;; // So far, so good. AVX2?
;; // Call cpuid with eax=7, ecx=0
;; int info2[4];
;; __cpuid_count(info2, 7, 0);
;; if ((info2[1] & (1 << 5)) != 0)
;; return 4;
;; else
;; return 3;
;; }
;; // Regular AVX
;; return 2;
;; }
;; else if ((info[2] & (1 << 19)) != 0)
;; return 1; // SSE4
;; else if ((info[3] & (1 << 26)) != 0)
;; return 0; // SSE2
;; else
;; abort();
;; }
define i32 @__get_system_isa() nounwind uwtable ssp {
entry:
%0 = tail call { i32, i32, i32, i32 } asm sideeffect "cpuid", "={ax},={bx},={cx},={dx},0,~{dirflag},~{fpsr},~{flags}"(i32 1) nounwind
%asmresult5.i = extractvalue { i32, i32, i32, i32 } %0, 2
%asmresult6.i = extractvalue { i32, i32, i32, i32 } %0, 3
%and = and i32 %asmresult5.i, 268435456
%cmp = icmp eq i32 %and, 0
br i1 %cmp, label %if.else13, label %if.then
if.then: ; preds = %entry
%1 = and i32 %asmresult5.i, 1610612736
%2 = icmp eq i32 %1, 1610612736
br i1 %2, label %if.then7, label %return
if.then7: ; preds = %if.then
%3 = tail call { i32, i32, i32, i32 } asm sideeffect "xchg$(l$)\09$(%$)ebx, $1\0A\09cpuid\0A\09xchg$(l$)\09$(%$)ebx, $1\0A\09", "={ax},=r,={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 7, i32 0) nounwind
%asmresult4.i28 = extractvalue { i32, i32, i32, i32 } %3, 1
%and10 = lshr i32 %asmresult4.i28, 5
%4 = and i32 %and10, 1
%5 = add i32 %4, 3
br label %return
if.else13: ; preds = %entry
%and15 = and i32 %asmresult5.i, 524288
%cmp16 = icmp eq i32 %and15, 0
br i1 %cmp16, label %if.else18, label %return
if.else18: ; preds = %if.else13
%and20 = and i32 %asmresult6.i, 67108864
%cmp21 = icmp eq i32 %and20, 0
br i1 %cmp21, label %if.else23, label %return
if.else23: ; preds = %if.else18
tail call void @abort() noreturn nounwind
unreachable
return: ; preds = %if.else18, %if.else13, %if.then7, %if.then
%retval.0 = phi i32 [ %5, %if.then7 ], [ 2, %if.then ], [ 1, %if.else13 ], [ 0, %if.else18 ]
ret i32 %retval.0
}
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; This function is called by each of the dispatch functions we generate;
;; it sets @__system_best_isa if it is unset.
define void @__set_system_isa() {
entry:
%bi = load i32* @__system_best_isa
%unset = icmp eq i32 %bi, -1
br i1 %unset, label %set_system_isa, label %done
set_system_isa:
%bival = call i32 @__get_system_isa()
store i32 %bival, i32* @__system_best_isa
ret void
done:
ret void
}