Remove alignment argument from memcpy/memmove/memset in favour of alignment attributes (Step 1)

Summary:
 This is a resurrection of work first proposed and discussed in Aug 2015:
   http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.html
and initially landed (but then backed out) in Nov 2015:
   http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html

 The @llvm.memcpy/memmove/memset intrinsics currently have an explicit argument
which is required to be a constant integer. It represents the alignment of the
dest (and source), and so must be the minimum of the actual alignment of the
two.

 This change is the first in a series that allows source and dest to each
have their own alignments by using the alignment attribute on their arguments.

 In this change we:
1) Remove the alignment argument.
2) Add alignment attributes to the source & dest arguments. We, temporarily,
   require that the alignments for source & dest be equal.

 For example, code which used to read:
  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dest, i8* %src, i32 100, i32 4, i1 false)
will now read
  call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 4 %dest, i8* align 4 %src, i32 100, i1 false)

 Downstream users may have to update their lit tests that check for
@llvm.memcpy/memmove/memset call/declaration patterns. The following extended sed script
may help with updating the majority of your tests, but it does not catch all possible
patterns so some manual checking and updating will be required.

s~declare void @llvm\.mem(set|cpy|move)\.p([^(]*)\((.*), i32, i1\)~declare void @llvm.mem\1.p\2(\3, i1)~g
s~call void @llvm\.memset\.p([^(]*)i8\(i8([^*]*)\* (.*), i8 (.*), i8 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i8(i8\2* \3, i8 \4, i8 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i16\(i8([^*]*)\* (.*), i8 (.*), i16 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i16(i8\2* \3, i8 \4, i16 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i32\(i8([^*]*)\* (.*), i8 (.*), i32 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i32(i8\2* \3, i8 \4, i32 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i64\(i8([^*]*)\* (.*), i8 (.*), i64 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i64(i8\2* \3, i8 \4, i64 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i128\(i8([^*]*)\* (.*), i8 (.*), i128 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i128(i8\2* \3, i8 \4, i128 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i8\(i8([^*]*)\* (.*), i8 (.*), i8 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i8(i8\2* align \6 \3, i8 \4, i8 \5, i1 \7)~g
s~call void @llvm\.memset\.p([^(]*)i16\(i8([^*]*)\* (.*), i8 (.*), i16 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i16(i8\2* align \6 \3, i8 \4, i16 \5, i1 \7)~g
s~call void @llvm\.memset\.p([^(]*)i32\(i8([^*]*)\* (.*), i8 (.*), i32 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i32(i8\2* align \6 \3, i8 \4, i32 \5, i1 \7)~g
s~call void @llvm\.memset\.p([^(]*)i64\(i8([^*]*)\* (.*), i8 (.*), i64 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i64(i8\2* align \6 \3, i8 \4, i64 \5, i1 \7)~g
s~call void @llvm\.memset\.p([^(]*)i128\(i8([^*]*)\* (.*), i8 (.*), i128 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i128(i8\2* align \6 \3, i8 \4, i128 \5, i1 \7)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i8\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i8 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i8(i8\3* \4, i8\5* \6, i8 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i16\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i16 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i16(i8\3* \4, i8\5* \6, i16 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i32\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i32 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i32(i8\3* \4, i8\5* \6, i32 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i64\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i64 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i64(i8\3* \4, i8\5* \6, i64 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i128\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i128 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i128(i8\3* \4, i8\5* \6, i128 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i8\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i8 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i8(i8\3* align \8 \4, i8\5* align \8 \6, i8 \7, i1 \9)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i16\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i16 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i16(i8\3* align \8 \4, i8\5* align \8 \6, i16 \7, i1 \9)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i32\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i32 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i32(i8\3* align \8 \4, i8\5* align \8 \6, i32 \7, i1 \9)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i64\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i64 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i64(i8\3* align \8 \4, i8\5* align \8 \6, i64 \7, i1 \9)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i128\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i128 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i128(i8\3* align \8 \4, i8\5* align \8 \6, i128 \7, i1 \9)~g

 The remaining changes in the series will:
Step 2) Expand the IRBuilder API to allow creation of memcpy/memmove with differing
   source and dest alignments.
Step 3) Update Clang to use the new IRBuilder API.
Step 4) Update Polly to use the new IRBuilder API.
Step 5) Update LLVM passes that create memcpy/memmove calls to use the new IRBuilder API,
        and those that use use MemIntrinsicInst::[get|set]Alignment() to use
        getDestAlignment() and getSourceAlignment() instead.
Step 6) Remove the single-alignment IRBuilder API for memcpy/memmove, and the
        MemIntrinsicInst::[get|set]Alignment() methods.

Reviewers: pete, hfinkel, lhames, reames, bollu

Reviewed By: reames

Subscribers: niosHD, reames, jholewinski, qcolombet, jfb, sanjoy, arsenm, dschuff, dylanmckay, mehdi_amini, sdardis, nemanjai, david2050, nhaehnle, javed.absar, sbc100, jgravelle-google, eraman, aheejin, kbarton, JDevlieghere, asb, rbar, johnrusso, simoncook, jordy.potman.lists, apazos, sabuasal, llvm-commits

Differential Revision: https://reviews.llvm.org/D41675

llvm-svn: 322965

1 files changed, 23 insertions, 28 deletions

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 3aeffc579b4..47afdf94a94 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -1064,6 +1064,8 @@ Currently, only the following parameter attributes are defined:
     to trap and to be properly aligned. This is not a valid attribute
     for return values.
 
+.. _attr_align:
+    
 ``align <n>``
     This indicates that the pointer value may be assumed by the optimizer to
     have the specified alignment.
@@ -10341,9 +10343,9 @@ support all bit widths however.
 ::
 
       declare void @llvm.memcpy.p0i8.p0i8.i32(i8* <dest>, i8* <src>,
-                                              i32 <len>, i32 <align>, i1 <isvolatile>)
+                                              i32 <len>, i1 <isvolatile>)
       declare void @llvm.memcpy.p0i8.p0i8.i64(i8* <dest>, i8* <src>,
-                                              i64 <len>, i32 <align>, i1 <isvolatile>)
+                                              i64 <len>, i1 <isvolatile>)
 
 Overview:
 """""""""
@@ -10352,7 +10354,7 @@ The '``llvm.memcpy.*``' intrinsics copy a block of memory from the
 source location to the destination location.
 
 Note that, unlike the standard libc function, the ``llvm.memcpy.*``
-intrinsics do not return a value, takes extra alignment/isvolatile
+intrinsics do not return a value, takes extra isvolatile
 arguments and the pointers can be in specified address spaces.
 
 Arguments:
@@ -10360,13 +10362,11 @@ Arguments:
 
 The first argument is a pointer to the destination, the second is a
 pointer to the source. The third argument is an integer argument
-specifying the number of bytes to copy, the fourth argument is the
-alignment of the source and destination locations, and the fifth is a
+specifying the number of bytes to copy, and the fourth is a
 boolean indicating a volatile access.
 
-If the call to this intrinsic has an alignment value that is not 0 or 1,
-then the caller guarantees that both the source and destination pointers
-are aligned to that boundary.
+The :ref:`align <_attr_align>` parameter attribute can be provided
+for the first and second arguments.
 
 If the ``isvolatile`` parameter is ``true``, the ``llvm.memcpy`` call is
 a :ref:`volatile operation <volatile>`. The detailed access behavior is not
@@ -10396,9 +10396,9 @@ bit widths however.
 ::
 
       declare void @llvm.memmove.p0i8.p0i8.i32(i8* <dest>, i8* <src>,
-                                               i32 <len>, i32 <align>, i1 <isvolatile>)
+                                               i32 <len>, i1 <isvolatile>)
       declare void @llvm.memmove.p0i8.p0i8.i64(i8* <dest>, i8* <src>,
-                                               i64 <len>, i32 <align>, i1 <isvolatile>)
+                                               i64 <len>, i1 <isvolatile>)
 
 Overview:
 """""""""
@@ -10409,21 +10409,19 @@ source location to the destination location. It is similar to the
 overlap.
 
 Note that, unlike the standard libc function, the ``llvm.memmove.*``
-intrinsics do not return a value, takes extra alignment/isvolatile
-arguments and the pointers can be in specified address spaces.
+intrinsics do not return a value, takes an extra isvolatile
+argument and the pointers can be in specified address spaces.
 
 Arguments:
 """"""""""
 
 The first argument is a pointer to the destination, the second is a
 pointer to the source. The third argument is an integer argument
-specifying the number of bytes to copy, the fourth argument is the
-alignment of the source and destination locations, and the fifth is a
+specifying the number of bytes to copy, and the fourth is a
 boolean indicating a volatile access.
 
-If the call to this intrinsic has an alignment value that is not 0 or 1,
-then the caller guarantees that the source and destination pointers are
-aligned to that boundary.
+The :ref:`align <_attr_align>` parameter attribute can be provided
+for the first and second arguments.
 
 If the ``isvolatile`` parameter is ``true``, the ``llvm.memmove`` call
 is a :ref:`volatile operation <volatile>`. The detailed access behavior is
@@ -10453,9 +10451,9 @@ support all bit widths.
 ::
 
       declare void @llvm.memset.p0i8.i32(i8* <dest>, i8 <val>,
-                                         i32 <len>, i32 <align>, i1 <isvolatile>)
+                                         i32 <len>, i1 <isvolatile>)
       declare void @llvm.memset.p0i8.i64(i8* <dest>, i8 <val>,
-                                         i64 <len>, i32 <align>, i1 <isvolatile>)
+                                         i64 <len>, i1 <isvolatile>)
 
 Overview:
 """""""""
@@ -10464,8 +10462,8 @@ The '``llvm.memset.*``' intrinsics fill a block of memory with a
 particular byte value.
 
 Note that, unlike the standard libc function, the ``llvm.memset``
-intrinsic does not return a value and takes extra alignment/volatile
-arguments. Also, the destination can be in an arbitrary address space.
+intrinsic does not return a value and takes an extra volatile
+argument. Also, the destination can be in an arbitrary address space.
 
 Arguments:
 """"""""""
@@ -10473,11 +10471,10 @@ Arguments:
 The first argument is a pointer to the destination to fill, the second
 is the byte value with which to fill it, the third argument is an
 integer argument specifying the number of bytes to fill, and the fourth
-argument is the known alignment of the destination location.
+is a boolean indicating a volatile access.
 
-If the call to this intrinsic has an alignment value that is not 0 or 1,
-then the caller guarantees that the destination pointer is aligned to
-that boundary.
+The :ref:`align <_attr_align>` parameter attribute can be provided
+for the first arguments.
 
 If the ``isvolatile`` parameter is ``true``, the ``llvm.memset`` call is
 a :ref:`volatile operation <volatile>`. The detailed access behavior is not
@@ -10487,9 +10484,7 @@ Semantics:
 """"""""""
 
 The '``llvm.memset.*``' intrinsics fill "len" bytes of memory starting
-at the destination location. If the argument is known to be aligned to
-some boundary, this can be specified as the fourth argument, otherwise
-it should be set to 0 or 1 (both meaning no alignment).
+at the destination location. 
 
 '``llvm.sqrt.*``' Intrinsic
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^