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1//===----------------------Hexagon builtin routine ------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// An optimized version of a memcpy which is equivalent to the following loop:10//11// volatile unsigned *dest;12// unsigned *src;13//14// for (i = 0; i < num_words; ++i)15// *dest++ = *src++;16//17// The corresponding C prototype for this function would be18// void hexagon_memcpy_forward_vp4cp4n2(volatile unsigned *dest,19// const unsigned *src,20// unsigned num_words);21//22// *** Both dest and src must be aligned to 32-bit boundaries. ***23// The code does not perform any runtime checks for this, and will fail24// in bad ways if this requirement is not met.25//26// The "forward" in the name refers to the fact that the function copies27// the words going forward in memory. It is incorrect to use this function28// for cases where the original code copied words in any other order.29//30// *** This function is only for the use by the compiler. ***31// The only indended use is for the LLVM compiler to generate calls to32// this function, when a mem-copy loop, like the one above, is detected.33 34 .text35 36// Inputs:37// r0: dest38// r1: src39// r2: num_words40 41 .globl hexagon_memcpy_forward_vp4cp4n242 .balign 3243 .type hexagon_memcpy_forward_vp4cp4n2,@function44hexagon_memcpy_forward_vp4cp4n2:45 46 // Compute r3 to be the number of words remaining in the current page.47 // At the same time, compute r4 to be the number of 32-byte blocks48 // remaining in the page (for prefetch).49 {50 r3 = sub(##4096, r1)51 r5 = lsr(r2, #3)52 }53 {54 // The word count before end-of-page is in the 12 lowest bits of r3.55 // (If the address in r1 was already page-aligned, the bits are 0.)56 r3 = extractu(r3, #10, #2)57 r4 = extractu(r3, #7, #5)58 }59 {60 r3 = minu(r2, r3)61 r4 = minu(r5, r4)62 }63 {64 r4 = or(r4, ##2105344) // 2105344 = 0x20200065 p0 = cmp.eq(r3, #0)66 if (p0.new) jump:nt .Lskipprolog67 }68 l2fetch(r1, r4)69 {70 loop0(.Lprolog, r3)71 r2 = sub(r2, r3) // r2 = number of words left after the prolog.72 }73 .falign74.Lprolog:75 {76 r4 = memw(r1++#4)77 memw(r0++#4) = r4.new78 } :endloop079.Lskipprolog:80 {81 // Let r3 = number of whole pages left (page = 1024 words).82 r3 = lsr(r2, #10)83 if (cmp.eq(r3.new, #0)) jump:nt .Lskipmain84 }85 {86 loop1(.Lout, r3)87 r2 = extractu(r2, #10, #0) // r2 = r2 & 102388 r3 = ##2105472 // r3 = 0x202080 (prefetch info)89 }90 // Iterate over pages.91 .falign92.Lout:93 // Prefetch each individual page.94 l2fetch(r1, r3)95 loop0(.Lpage, #512)96 .falign97.Lpage:98 r5:4 = memd(r1++#8)99 {100 memw(r0++#8) = r4101 memw(r0+#4) = r5102 } :endloop0:endloop1103.Lskipmain:104 {105 r3 = ##2105344 // r3 = 0x202000 (prefetch info)106 r4 = lsr(r2, #3) // r4 = number of 32-byte blocks remaining.107 p0 = cmp.eq(r2, #0)108 if (p0.new) jumpr:nt r31109 }110 {111 r3 = or(r3, r4)112 loop0(.Lepilog, r2)113 }114 l2fetch(r1, r3)115 .falign116.Lepilog:117 {118 r4 = memw(r1++#4)119 memw(r0++#4) = r4.new120 } :endloop0121 122 jumpr r31123 124.size hexagon_memcpy_forward_vp4cp4n2, . - hexagon_memcpy_forward_vp4cp4n2125