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Fix __load_masked_{32,64} to properly obey the mask. Fixes issue #28.

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Fixed the implementations of these builtin functions for targets that don't have native masked load instructions so that they do no loads if the vector mask is all off, and only do an (unaligned) vector load if both the first and last element of the mask are on.  Otherwise they serialize and do scalar loads for only the active lanes.  This fixes a number of potential sources of crashes due to accessing invalid memory.
This commit is contained in:
Matt Pharr
2011-07-08 11:21:11 +01:00
parent 092d288aef
commit e156651190
3 changed files with 92 additions and 123 deletions
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51
stdlib-sse4x2.ll
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@@ -463,53 +463,10 @@ define void @__masked_store_64(<8 x i64>* nocapture, <8 x i64>,
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; unaligned loads/loads+broadcasts
; FIXME: I think this and the next one need to verify that the mask isn't
; all off before doing the load!!! (See e.g. stdlib-sse.ll)
define <8 x i32> @__load_and_broadcast_32(i8 *, <8 x i32> %mask) nounwind alwaysinline {
%ptr = bitcast i8 * %0 to i32 *
%val = load i32 * %ptr
%ret0 = insertelement <8 x i32> undef, i32 %val, i32 0
%ret1 = insertelement <8 x i32> %ret0, i32 %val, i32 1
%ret2 = insertelement <8 x i32> %ret1, i32 %val, i32 2
%ret3 = insertelement <8 x i32> %ret2, i32 %val, i32 3
%ret4 = insertelement <8 x i32> %ret3, i32 %val, i32 4
%ret5 = insertelement <8 x i32> %ret4, i32 %val, i32 5
%ret6 = insertelement <8 x i32> %ret5, i32 %val, i32 6
%ret7 = insertelement <8 x i32> %ret6, i32 %val, i32 7
ret <8 x i32> %ret7
}
define <8 x i64> @__load_and_broadcast_64(i8 *, <8 x i32> %mask) nounwind alwaysinline {
%ptr = bitcast i8 * %0 to i64 *
%val = load i64 * %ptr
%ret0 = insertelement <8 x i64> undef, i64 %val, i32 0
%ret1 = insertelement <8 x i64> %ret0, i64 %val, i32 1
%ret2 = insertelement <8 x i64> %ret1, i64 %val, i32 2
%ret3 = insertelement <8 x i64> %ret2, i64 %val, i32 3
%ret4 = insertelement <8 x i64> %ret3, i64 %val, i32 4
%ret5 = insertelement <8 x i64> %ret4, i64 %val, i32 5
%ret6 = insertelement <8 x i64> %ret5, i64 %val, i32 6
%ret7 = insertelement <8 x i64> %ret6, i64 %val, i32 7
ret <8 x i64> %ret7
}
define <8 x i32> @__load_masked_32(i8 *, <8 x i32> %mask) nounwind alwaysinline {
%ptr = bitcast i8 * %0 to <8 x i32> *
%val = load <8 x i32> * %ptr, align 4
ret <8 x i32> %val
}
define <8 x i64> @__load_masked_64(i8 *, <8 x i32> %mask) nounwind alwaysinline {
%ptr = bitcast i8 * %0 to <8 x i64> *
%val = load <8 x i64> * %ptr, align 8
ret <8 x i64> %val
}
load_and_broadcast(8, i32, 32)
load_and_broadcast(8, i64, 64)
load_masked(8, i32, 32, 4)
load_masked(8, i64, 64, 8)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; gather/scatter