Lines Matching full:mca
30 .TH "LLVM-MCA" "1" "2023-05-24" "16" "LLVM"
32 llvm-mca \- LLVM Machine Code Analyzer
35 \fBllvm\-mca\fP [\fIoptions\fP] [input]
38 \fBllvm\-mca\fP is a performance analysis tool that uses information
50 Given an assembly code sequence, \fBllvm\-mca\fP estimates the Instructions
55 directly into \fBllvm\-mca\fP for analysis:
61 $ clang foo.c \-O2 \-target x86_64\-unknown\-unknown \-S \-o \- | llvm\-mca \-mcpu=btver2
73 …rget x86_64\-unknown\-unknown \-mllvm \-x86\-asm\-syntax=intel \-S \-o \- | llvm\-mca \-mcpu=btver2
79 (\fBllvm\-mca\fP detects Intel syntax by the presence of an \fI\&.intel_syntax\fP
87 By design, the quality of the analysis conducted by \fBllvm\-mca\fP is
95 If \fBinput\fP is \(dq\fB\-\fP\(dq or omitted, \fBllvm\-mca\fP reads from standard
98 If the \fI\%\-o\fP option is omitted, then \fBllvm\-mca\fP will send its output
302 \fBllvm\-mca\fP returns 0 on success. Otherwise, an error message is printed
306 \fBllvm\-mca\fP allows for the optional usage of special code comments to
308 substring \fBLLVM\-MCA\-BEGIN\fP marks the beginning of an analysis region. A
309 comment starting with substring \fBLLVM\-MCA\-END\fP marks the end of a region.
316 # LLVM\-MCA\-BEGIN
318 # LLVM\-MCA\-END
324 If no user\-defined region is specified, then \fBllvm\-mca\fP assumes a
335 # LLVM\-MCA\-BEGIN A simple example
337 # LLVM\-MCA\-END
345 in the \fBLLVM\-MCA\-END\fP directive. In the absence of overlapping regions,
346 an anonymous \fBLLVM\-MCA\-END\fP directive always ends the currently active user
355 # LLVM\-MCA\-BEGIN foo
357 # LLVM\-MCA\-BEGIN bar
359 # LLVM\-MCA\-END bar
360 # LLVM\-MCA\-END foo
372 # LLVM\-MCA\-BEGIN foo
374 # LLVM\-MCA\-BEGIN bar
376 # LLVM\-MCA\-END foo
378 # LLVM\-MCA\-END bar
395 __asm volatile(\(dq# LLVM\-MCA\-BEGIN foo\(dq:::\(dqmemory\(dq);
397 __asm volatile(\(dq# LLVM\-MCA\-END\(dq:::\(dqmemory\(dq);
417 special LLVM\-MCA comment directives.
423 # LLVM\-MCA\-<INSTRUMENT_TYPE> <data>
433 A comment starting with substring \fILLVM\-MCA\-<INSTRUMENT_TYPE>\fP
434 brings data into scope for llvm\-mca to use in its analysis for
445 Comments that are prefixed with \fILLVM\-MCA\-\fP but do not correspond to
448 that do not start with \fILLVM\-MCA\-\fP are ignored by :program \fIllvm\-mca\fP\&.
461 # LLVM\-MCA\-RISCV\-LMUL <M1|M2|M4|M8|MF2|MF4|MF8>
479 # LLVM\-MCA\-RISCV\-LMUL M2
493 # LLVM\-MCA\-RISCV\-LMUL M1
507 # LLVM\-MCA\-RISCV\-LMUL M1
510 # LLVM\-MCA\-RISCV\-LMUL M8
524 # LLVM\-MCA\-RISCV\-LMUL M1
527 # LLVM\-MCA\-RISCV\-LMUL M4
533 .SH HOW LLVM-MCA WORKS
535 \fBllvm\-mca\fP takes assembly code as input. The assembly code is parsed
549 \fBtest/tools/llvm\-mca/X86/BtVer2/dot\-product.s\fP:
555 $ llvm\-mca \-mtriple=x86_64\-unknown\-unknown \-mcpu=btver2 \-iterations=300 dot\-product.s
757 \fBtest/tools/llvm\-mca/X86/BtVer2/dot\-product.s\fP and processed by
758 \fBllvm\-mca\fP using the following command:
764 $ llvm\-mca \-mtriple=x86_64\-unknown\-unknown \-mcpu=btver2 \-iterations=3 \-timeline dot\-product…
861 instructions measured. Note that \fBllvm\-mca\fP, by default, assumes at
883 \fBllvm\-mca\fP for 500 iterations of the dot\-product example on btver2.
939 Below is an example of \fB\-all\-stats\fP output generated by \fBllvm\-mca\fP
1075 \fBllvm\-mca\fP, as well as the functional units involved in the process.
1094 \fBllvm\-mca\fP assumes that instructions have all been decoded and placed
1097 diagnosed. Also, \fBllvm\-mca\fP does not model branch prediction.
1121 the processor. \fBllvm\-mca\fP uses that information to initialize register
1136 entries. \fBllvm\-mca\fP queries the scheduling model to determine the set
1145 Instruction latencies are computed by \fBllvm\-mca\fP with the help of the
1148 \fBllvm\-mca\fP\(aqs scheduler is designed to simulate multiple processor
1159 \fBllvm\-mca\fP\(aqs scheduler internally groups instructions into three sets:
1190 To simulate an out\-of\-order execution of memory operations, \fBllvm\-mca\fP
1242 \fBllvm\-mca\fP does not (on its own) know about serializing operations or
1247 IsAStoreBarrier and IsALoadBarrier flag. These flags are mca specific and
1251 within \fIllvm/lib/Target/X86/MCA/X86CustomBehaviour.cpp\fP\&.
1284 retire. \fBllvm\-mca\fP ensures that writes are committed in\-order. However,
1290 scheduling model, \fBllvm\-mca\fP isn\(aqt always able to simulate them
1296 hazards that \fBllvm\-mca\fP has no way of knowing about).
1298 \fBllvm\-mca\fP comes with one generic and multiple target specific
1315 example \fI/llvm/lib/Target/AMDGPU/MCA/\fP) so that they can access backend symbols.
1324 and \fIvl\fP change the scheduling behaviour of vector instructions. Since MCA
1339 \fBllvm\-mca\fP comes with several Views such as the Timeline View and
1341 targets. If you wish to add a new View to \fBllvm\-mca\fP and it does not
1344 \fI/tools/llvm\-mca/View/\fP directory. However, if your new View is target specific
1346 the \fI/lib/Target/<TargetName>/MCA/\fP directory.