Add CR-bit tracking to the PowerPC backend for i1 values
This change enables tracking i1 values in the PowerPC backend using the
condition register bits. These bits can be treated on PowerPC as separate
registers; individual bit operations (and, or, xor, etc.) are supported.
Tracking booleans in CR bits has several advantages:
- Reduction in register pressure (because we no longer need GPRs to store
boolean values).
- Logical operations on booleans can be handled more efficiently; we used to
have to move all results from comparisons into GPRs, perform promoted
logical operations in GPRs, and then move the result back into condition
register bits to be used by conditional branches. This can be very
inefficient, because the throughput of these CR <-> GPR moves have high
latency and low throughput (especially when other associated instructions
are accounted for).
- On the POWER7 and similar cores, we can increase total throughput by using
the CR bits. CR bit operations have a dedicated functional unit.
Most of this is more-or-less mechanical: Adjustments were needed in the
calling-convention code, support was added for spilling/restoring individual
condition-register bits, and conditional branch instruction definitions taking
specific CR bits were added (plus patterns and code for generating bit-level
operations).
This is enabled by default when running at -O2 and higher. For -O0 and -O1,
where the ability to debug is more important, this feature is disabled by
default. Individual CR bits do not have assigned DWARF register numbers,
and storing values in CR bits makes them invisible to the debugger.
It is critical, however, that we don't move i1 values that have been promoted
to larger values (such as those passed as function arguments) into bit
registers only to quickly turn around and move the values back into GPRs (such
as happens when values are returned by functions). A pair of target-specific
DAG combines are added to remove the trunc/extends in:
trunc(binary-ops(binary-ops(zext(x), zext(y)), ...)
and:
zext(binary-ops(binary-ops(trunc(x), trunc(y)), ...)
In short, we only want to use CR bits where some of the i1 values come from
comparisons or are used by conditional branches or selects. To put it another
way, if we can do the entire i1 computation in GPRs, then we probably should
(on the POWER7, the GPR-operation throughput is higher, and for all cores, the
CR <-> GPR moves are expensive).
POWER7 test-suite performance results (from 10 runs in each configuration):
SingleSource/Benchmarks/Misc/mandel-2: 35% speedup
MultiSource/Benchmarks/Prolangs-C++/city/city: 21% speedup
MultiSource/Benchmarks/MiBench/automotive-susan: 23% speedup
SingleSource/Benchmarks/CoyoteBench/huffbench: 13% speedup
SingleSource/Benchmarks/Misc-C++/Large/sphereflake: 13% speedup
SingleSource/Benchmarks/Misc-C++/mandel-text: 10% speedup
SingleSource/Benchmarks/Misc-C++-EH/spirit: 10% slowdown
MultiSource/Applications/lemon/lemon: 8% slowdown
llvm-svn: 202451
2014-02-28 08:27:01 +08:00
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; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -mattr=-crbits | FileCheck %s
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; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 | FileCheck %s -check-prefix=CHECK-CRB
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2013-04-10 06:58:37 +08:00
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target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64"
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target triple = "powerpc64-unknown-linux-gnu"
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%struct.lua_TValue.17.692 = type { %union.Value.16.691, i32 }
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%union.Value.16.691 = type { %union.GCObject.15.690* }
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%union.GCObject.15.690 = type { %struct.lua_State.14.689 }
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%struct.lua_State.14.689 = type { %union.GCObject.15.690*, i8, i8, i8, %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692*, %struct.global_State.10.685*, %struct.CallInfo.11.686*, i32*, %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692*, %struct.CallInfo.11.686*, %struct.CallInfo.11.686*, i32, i32, i16, i16, i8, i8, i32, i32, void (%struct.lua_State.14.689*, %struct.lua_Debug.12.687*)*, %struct.lua_TValue.17.692, %struct.lua_TValue.17.692, %union.GCObject.15.690*, %union.GCObject.15.690*, %struct.lua_longjmp.13.688*, i64 }
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%struct.global_State.10.685 = type { %struct.stringtable.0.675, i8* (i8*, i8*, i64, i64)*, i8*, i8, i8, i32, %union.GCObject.15.690*, %union.GCObject.15.690**, %union.GCObject.15.690*, %union.GCObject.15.690*, %union.GCObject.15.690*, %union.GCObject.15.690*, %struct.Mbuffer.1.676, i64, i64, i64, i64, i32, i32, i32 (%struct.lua_State.14.689*)*, %struct.lua_TValue.17.692, %struct.lua_State.14.689*, %struct.UpVal.3.678, [9 x %struct.Table.7.682*], [17 x %union.TString.9.684*] }
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%struct.stringtable.0.675 = type { %union.GCObject.15.690**, i32, i32 }
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%struct.Mbuffer.1.676 = type { i8*, i64, i64 }
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%struct.UpVal.3.678 = type { %union.GCObject.15.690*, i8, i8, %struct.lua_TValue.17.692*, %union.anon.2.677 }
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%union.anon.2.677 = type { %struct.lua_TValue.17.692 }
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%struct.Table.7.682 = type { %union.GCObject.15.690*, i8, i8, i8, i8, %struct.Table.7.682*, %struct.lua_TValue.17.692*, %struct.Node.6.681*, %struct.Node.6.681*, %union.GCObject.15.690*, i32 }
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%struct.Node.6.681 = type { %struct.lua_TValue.17.692, %union.TKey.5.680 }
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%union.TKey.5.680 = type { %struct.anon.0.4.679 }
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%struct.anon.0.4.679 = type { %union.Value.16.691, i32, %struct.Node.6.681* }
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%union.TString.9.684 = type { %struct.anon.1.8.683 }
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%struct.anon.1.8.683 = type { %union.GCObject.15.690*, i8, i8, i8, i32, i64 }
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%struct.CallInfo.11.686 = type { %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692*, i32*, i32, i32 }
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%struct.lua_Debug.12.687 = type { i32, i8*, i8*, i8*, i8*, i32, i32, i32, i32, [60 x i8], i32 }
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%struct.lua_longjmp.13.688 = type opaque
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define void @lua_xmove(i32 signext %n) #0 {
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entry:
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br i1 undef, label %for.end, label %if.end
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if.end: ; preds = %entry
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br i1 undef, label %for.body.lr.ph, label %for.end
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for.body.lr.ph: ; preds = %if.end
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br label %for.body
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for.body: ; preds = %for.body.for.body_crit_edge, %for.body.lr.ph
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%0 = phi %struct.lua_TValue.17.692* [ undef, %for.body.lr.ph ], [ %.pre, %for.body.for.body_crit_edge ]
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%indvars.iv = phi i64 [ 0, %for.body.lr.ph ], [ %indvars.iv.next, %for.body.for.body_crit_edge ]
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[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
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%tt = getelementptr inbounds %struct.lua_TValue.17.692, %struct.lua_TValue.17.692* %0, i64 %indvars.iv, i32 1
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2015-02-28 05:17:42 +08:00
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%1 = load i32, i32* %tt, align 4
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2013-08-22 06:20:53 +08:00
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store i32 %1, i32* undef, align 4
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2013-04-10 06:58:37 +08:00
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%indvars.iv.next = add i64 %indvars.iv, 1
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%lftr.wideiv = trunc i64 %indvars.iv.next to i32
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%exitcond = icmp eq i32 %lftr.wideiv, %n
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br i1 %exitcond, label %for.end, label %for.body.for.body_crit_edge
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for.body.for.body_crit_edge: ; preds = %for.body
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2015-02-28 05:17:42 +08:00
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%.pre = load %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692** undef, align 8
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2013-04-10 06:58:37 +08:00
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br label %for.body
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for.end: ; preds = %for.body, %if.end, %entry
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ret void
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; CHECK: @lua_xmove
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; CHECK: bnelr
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; CHECK: bnelr
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; CHECK: bdzlr
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2013-04-11 06:05:25 +08:00
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; CHECK-NOT: blr
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Add CR-bit tracking to the PowerPC backend for i1 values
This change enables tracking i1 values in the PowerPC backend using the
condition register bits. These bits can be treated on PowerPC as separate
registers; individual bit operations (and, or, xor, etc.) are supported.
Tracking booleans in CR bits has several advantages:
- Reduction in register pressure (because we no longer need GPRs to store
boolean values).
- Logical operations on booleans can be handled more efficiently; we used to
have to move all results from comparisons into GPRs, perform promoted
logical operations in GPRs, and then move the result back into condition
register bits to be used by conditional branches. This can be very
inefficient, because the throughput of these CR <-> GPR moves have high
latency and low throughput (especially when other associated instructions
are accounted for).
- On the POWER7 and similar cores, we can increase total throughput by using
the CR bits. CR bit operations have a dedicated functional unit.
Most of this is more-or-less mechanical: Adjustments were needed in the
calling-convention code, support was added for spilling/restoring individual
condition-register bits, and conditional branch instruction definitions taking
specific CR bits were added (plus patterns and code for generating bit-level
operations).
This is enabled by default when running at -O2 and higher. For -O0 and -O1,
where the ability to debug is more important, this feature is disabled by
default. Individual CR bits do not have assigned DWARF register numbers,
and storing values in CR bits makes them invisible to the debugger.
It is critical, however, that we don't move i1 values that have been promoted
to larger values (such as those passed as function arguments) into bit
registers only to quickly turn around and move the values back into GPRs (such
as happens when values are returned by functions). A pair of target-specific
DAG combines are added to remove the trunc/extends in:
trunc(binary-ops(binary-ops(zext(x), zext(y)), ...)
and:
zext(binary-ops(binary-ops(trunc(x), trunc(y)), ...)
In short, we only want to use CR bits where some of the i1 values come from
comparisons or are used by conditional branches or selects. To put it another
way, if we can do the entire i1 computation in GPRs, then we probably should
(on the POWER7, the GPR-operation throughput is higher, and for all cores, the
CR <-> GPR moves are expensive).
POWER7 test-suite performance results (from 10 runs in each configuration):
SingleSource/Benchmarks/Misc/mandel-2: 35% speedup
MultiSource/Benchmarks/Prolangs-C++/city/city: 21% speedup
MultiSource/Benchmarks/MiBench/automotive-susan: 23% speedup
SingleSource/Benchmarks/CoyoteBench/huffbench: 13% speedup
SingleSource/Benchmarks/Misc-C++/Large/sphereflake: 13% speedup
SingleSource/Benchmarks/Misc-C++/mandel-text: 10% speedup
SingleSource/Benchmarks/Misc-C++-EH/spirit: 10% slowdown
MultiSource/Applications/lemon/lemon: 8% slowdown
llvm-svn: 202451
2014-02-28 08:27:01 +08:00
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; CHECK-CRB: @lua_xmove
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; CHECK-CRB: bclr 12,
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; CHECK-CRB: bclr 12,
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; CHECK-CRB: bdzlr
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; CHECK-CRB-NOT: blr
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2013-04-10 06:58:37 +08:00
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}
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attributes #0 = { nounwind }
|