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llvm-project/llvm/test/CodeGen/X86/phielim-split.ll

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During PHI elimination, split critical edges that move copies out of loops. This prevents the behavior observed in llvm.org/PR22369. I am not sure whether I am reading the code correctly, but the early exit based on isLiveOutPastPHIs() seems to make the wrong assumption that RegisterCoalescer won't be able to coalesce those copies later. This change hides the new behavior behind -no-phi-elim-live-out-early-exit as it currently breaks four tests: * Assertion in: CodeGen/Hexagon/hwloop-cleanup.ll * Worse code in: CodeGen/X86/coalescer-commute4.ll CodeGen/X86/phys_subreg_coalesce-2.ll CodeGen/X86/zlib-longest-match.ll The root cause here seems to be that the heuristic that determines the visitation order in RegisterCoalescer gets less lucky. llvm-svn: 231064
2015-03-03 18:23:11 +08:00
; RUN: llc < %s -verify-machineinstrs -no-phi-elim-live-out-early-exit | FileCheck %s
Split loop exiting edges more aggressively. PHIElimination splits critical edges when it predicts it can resolve interference and eliminate copies. It doesn't split the edge if the interference wouldn't be resolved anyway because the phi-use register is live in the critical edge anyway. Teach PHIElimination to split loop exiting edges with interference, even if it wouldn't resolve the interference. This removes the necessary copies from the loop, which is still an improvement from injecting the copies into the loop. The test case demonstrates the improvement. Before: LBB0_1: cmpb $0, (%rdx) leaq 1(%rdx), %rdx movl %esi, %eax je LBB0_1 After: LBB0_1: cmpb $0, (%rdx) leaq 1(%rdx), %rdx je LBB0_1 movl %esi, %eax llvm-svn: 160571
2012-07-21 04:49:53 +08:00
target triple = "x86_64-apple-macosx10.8.0"
; The critical edge from for.cond to if.end2 should be split to avoid injecting
; copies into the loop. The use of %b after the loop causes interference that
; makes a copy necessary.
; <rdar://problem/11561842>
;
; CHECK: split_loop_exit
; CHECK: %for.cond
; CHECK-NOT: mov
; CHECK: je
define i32 @split_loop_exit(i32 %a, i32 %b, i8* nocapture %p) nounwind uwtable readonly ssp {
entry:
%cmp = icmp sgt i32 %a, 10
br i1 %cmp, label %for.cond, label %if.end2
for.cond: ; preds = %entry, %for.cond
%p.addr.0 = phi i8* [ %incdec.ptr, %for.cond ], [ %p, %entry ]
[opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction One of several parallel first steps to remove the target type of pointers, replacing them with a single opaque pointer type. This adds an explicit type parameter to the gep instruction so that when the first parameter becomes an opaque pointer type, the type to gep through is still available to the instructions. * This doesn't modify gep operators, only instructions (operators will be handled separately) * Textual IR changes only. Bitcode (including upgrade) and changing the in-memory representation will be in separate changes. * geps of vectors are transformed as: getelementptr <4 x float*> %x, ... ->getelementptr float, <4 x float*> %x, ... Then, once the opaque pointer type is introduced, this will ultimately look like: getelementptr float, <4 x ptr> %x with the unambiguous interpretation that it is a vector of pointers to float. * address spaces remain on the pointer, not the type: getelementptr float addrspace(1)* %x ->getelementptr float, float addrspace(1)* %x Then, eventually: getelementptr float, ptr addrspace(1) %x Importantly, the massive amount of test case churn has been automated by same crappy python code. I had to manually update a few test cases that wouldn't fit the script's model (r228970,r229196,r229197,r229198). The python script just massages stdin and writes the result to stdout, I then wrapped that in a shell script to handle replacing files, then using the usual find+xargs to migrate all the files. update.py: import fileinput import sys import re ibrep = re.compile(r"(^.*?[^%\w]getelementptr inbounds )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))") normrep = re.compile( r"(^.*?[^%\w]getelementptr )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))") def conv(match, line): if not match: return line line = match.groups()[0] if len(match.groups()[5]) == 0: line += match.groups()[2] line += match.groups()[3] line += ", " line += match.groups()[1] line += "\n" return line for line in sys.stdin: if line.find("getelementptr ") == line.find("getelementptr inbounds"): if line.find("getelementptr inbounds") != line.find("getelementptr inbounds ("): line = conv(re.match(ibrep, line), line) elif line.find("getelementptr ") != line.find("getelementptr ("): line = conv(re.match(normrep, line), line) sys.stdout.write(line) apply.sh: for name in "$@" do python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name" rm -f "$name.tmp" done The actual commands: From llvm/src: find test/ -name *.ll | xargs ./apply.sh From llvm/src/tools/clang: find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}" From llvm/src/tools/polly: find test/ -name *.ll | xargs ./apply.sh After that, check-all (with llvm, clang, clang-tools-extra, lld, compiler-rt, and polly all checked out). The extra 'rm' in the apply.sh script is due to a few files in clang's test suite using interesting unicode stuff that my python script was throwing exceptions on. None of those files needed to be migrated, so it seemed sufficient to ignore those cases. Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7636 llvm-svn: 230786
2015-02-28 03:29:02 +08:00
%incdec.ptr = getelementptr inbounds i8, i8* %p.addr.0, i64 1
[opaque pointer type] Add textual IR support for explicit type parameter to load instruction Essentially the same as the GEP change in r230786. A similar migration script can be used to update test cases, though a few more test case improvements/changes were required this time around: (r229269-r229278) import fileinput import sys import re pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)") for line in sys.stdin: sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line)) Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7649 llvm-svn: 230794
2015-02-28 05:17:42 +08:00
%0 = load i8, i8* %p.addr.0, align 1
Split loop exiting edges more aggressively. PHIElimination splits critical edges when it predicts it can resolve interference and eliminate copies. It doesn't split the edge if the interference wouldn't be resolved anyway because the phi-use register is live in the critical edge anyway. Teach PHIElimination to split loop exiting edges with interference, even if it wouldn't resolve the interference. This removes the necessary copies from the loop, which is still an improvement from injecting the copies into the loop. The test case demonstrates the improvement. Before: LBB0_1: cmpb $0, (%rdx) leaq 1(%rdx), %rdx movl %esi, %eax je LBB0_1 After: LBB0_1: cmpb $0, (%rdx) leaq 1(%rdx), %rdx je LBB0_1 movl %esi, %eax llvm-svn: 160571
2012-07-21 04:49:53 +08:00
%tobool = icmp eq i8 %0, 0
br i1 %tobool, label %for.cond, label %if.end2
if.end2: ; preds = %for.cond, %entry
%r.0 = phi i32 [ %a, %entry ], [ %b, %for.cond ]
%add = add nsw i32 %r.0, %b
ret i32 %add
}
During PHI elimination, split critical edges that move copies out of loops. This prevents the behavior observed in llvm.org/PR22369. I am not sure whether I am reading the code correctly, but the early exit based on isLiveOutPastPHIs() seems to make the wrong assumption that RegisterCoalescer won't be able to coalesce those copies later. This change hides the new behavior behind -no-phi-elim-live-out-early-exit as it currently breaks four tests: * Assertion in: CodeGen/Hexagon/hwloop-cleanup.ll * Worse code in: CodeGen/X86/coalescer-commute4.ll CodeGen/X86/phys_subreg_coalesce-2.ll CodeGen/X86/zlib-longest-match.ll The root cause here seems to be that the heuristic that determines the visitation order in RegisterCoalescer gets less lucky. llvm-svn: 231064
2015-03-03 18:23:11 +08:00
; CHECK: split_live_out
; CHECK: %while.body
; CHECK: cmp
; CHECK-NEXT: ja
define i8* @split_live_out(i32 %value, i8* %target) nounwind uwtable readonly ssp {
entry:
%cmp10 = icmp ugt i32 %value, 127
br i1 %cmp10, label %while.body.preheader, label %while.end
while.body.preheader: ; preds = %entry
br label %while.body
while.body: ; preds = %while.body.preheader, %while.body
%target.addr.012 = phi i8* [ %incdec.ptr, %while.body ], [ %target, %while.body.preheader ]
%value.addr.011 = phi i32 [ %shr, %while.body ], [ %value, %while.body.preheader ]
%or = or i32 %value.addr.011, 128
%conv = trunc i32 %or to i8
store i8 %conv, i8* %target.addr.012, align 1
%shr = lshr i32 %value.addr.011, 7
%incdec.ptr = getelementptr inbounds i8, i8* %target.addr.012, i64 1
%cmp = icmp ugt i32 %value.addr.011, 16383
br i1 %cmp, label %while.body, label %while.end.loopexit
while.end.loopexit: ; preds = %while.body
%incdec.ptr.lcssa = phi i8* [ %incdec.ptr, %while.body ]
%shr.lcssa = phi i32 [ %shr, %while.body ]
br label %while.end
while.end: ; preds = %while.end.loopexit, %entry
%target.addr.0.lcssa = phi i8* [ %target, %entry ], [ %incdec.ptr.lcssa, %while.end.loopexit ]
%value.addr.0.lcssa = phi i32 [ %value, %entry ], [ %shr.lcssa, %while.end.loopexit ]
%conv1 = trunc i32 %value.addr.0.lcssa to i8
store i8 %conv1, i8* %target.addr.0.lcssa, align 1
%incdec.ptr3 = getelementptr inbounds i8, i8* %target.addr.0.lcssa, i64 1
ret i8* %incdec.ptr3
}