1LLVM-REMARK-SIZE-DIFF(1)             LLVM             LLVM-REMARK-SIZE-DIFF(1)
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NAME

6       llvm-remark-size-diff - diff size remarks
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SYNOPSIS

9       llvm-remark-size-diff [options] file_a file_b --parser parser
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DESCRIPTION

12       llvm-remark-size-diff  diffs  size  remarks in two remark files: file_a
13       and file_b.
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15       llvm-remark-size-diff can be used to gain insight into which  functions
16       were impacted the most by code generation changes.
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18       In  most  common  use-cases file_a and file_b will be remarks output by
19       compiling a fixed source with differing compilers  or  differing  opti‐
20       mization settings.
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22       llvm-remark-size-diff handles both YAML and bitstream remarks.
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OPTIONS

25       --parser=<yaml|bitstream>
26              Select  the  type of input remark parser. Required.  * yaml: The
27              tool will parse YAML remarks.  * bitstream: The tool will  parse
28              bitstream remarks.
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30       --report-style=<human|json>
31              Output  style.   * human: Human-readable textual report. Default
32              option.  * json: JSON report.
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34       --pretty
35              Pretty-print JSON output. Optional.
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37              If output is not set to JSON, this does nothing.
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39       -o=<file>
40              Output file for the report. Outputs to stdout by default.
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HUMAN-READABLE OUTPUT

43       The human-readable format for llvm-remark-size-diff is composed of  two
44       sections:
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46       • Per-function changes.
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48       • A high-level summary of all changes.
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50   Changed Function Section
51       Suppose you are comparing two remark files OLD and NEW.
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53       For  each  function  with  a  changed instruction count in OLD and NEW,
54       llvm-remark-size-diff will emit a line like below:
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56          (++|--|==) (>|<) function_name, N instrs, M stack B
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58       A breakdown of the format is below:
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60       (++|--|==)
61              Which of OLD and NEW the function_name is present in.
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63              • ++: Only in NEW. ("Added")
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65              • --: Only in OLD. ("Removed")
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67              • ==: In both.
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69       (>|<)  Denotes if function_name has more instructions or fewer instruc‐
70              tions in the second file.
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72              • >: More instructions in second file than first file.
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74              • <: Fewer instructions in second file than in first file.
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76       function_name
77              The name of the changed function.
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79       N instrs
80              Second file instruction count - first file instruction count.
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82       M stack B
83              Second file stack byte count - first file stack byte count.
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85   Summary Section
86       llvm-remark-size-diff  will  output a high-level summary after printing
87       all changed functions.
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89          instruction count: N (inst_pct_change%)
90          stack byte usage: M (sb_pct_change%)
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92       N      Sum of all instruction count  changes  between  the  second  and
93              first file.
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95       inst_pct_change%
96              Percent  increase  or  decrease in instruction count between the
97              second and first file.
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99       M      Sum of all stack byte count changes between the second and first
100              file.
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102       sb_pct_change%
103              Percent  increase  or  decrease  in stack byte usage between the
104              second and first file.
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JSON OUTPUT

107   High-Level view
108       Suppose we are comparing two files, OLD and NEW.
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110       llvm-remark-size-diff will output JSON as follows.
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112          "Files": [
113            "A": "path/to/OLD",
114            "B": "path/to/NEW"
115          ]
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117          "InBoth": [
118            ...
119          ],
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121          "OnlyInA": [
122            ...
123          ],
124
125          "OnlyInB": [
126            ...
127          ]
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129       Files  Original paths to remark files.
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131              • A: Path to the first file.
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133              • B: Path to the second file.
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135       InBoth Functions present in both files.
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137       OnlyInA
138              Functions only present in the first file.
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140       OnlyInB
141              Functions only present in the second file.
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143   Function JSON
144       The InBoth, OnlyInA, and OnlyInB sections contain size information  for
145       each function in the input remark files.
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147          {
148            "FunctionName" : "function_name"
149            "InstCount": [
150                INST_COUNT_A,
151                INST_COUNT_B
152              ],
153            "StackSize": [
154                STACK_BYTES_A,
155                STACK_BYTES_B
156              ],
157          }
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159       FunctionName
160              Name of the function.
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162       InstCount
163              Instruction counts for the function.
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165              • INST_COUNT_A: Instruction count in OLD.
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167              • INST_COUNT_B: Instruction count in NEW.
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169       StackSize
170              Stack byte counts for the function.
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172              • STACK_BYTES_A: Stack bytes in OLD.
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174              • STACK_BYTES_B: Stack bytes in NEW.
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176   Computing Diffs From Function JSON
177       Function  JSON  does not contain the diffs. Tools consuming JSON output
178       from llvm-remark-size-diff are responsible for computing the diffs sep‐
179       arately.
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181       To compute the diffs:
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183       • Instruction count diff: INST_COUNT_B - INST_COUNT_A
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185       • Stack byte count diff: STACK_BYTES_B - STACK_BYTES_A
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EXIT STATUS

188       llvm-remark-size-diff returns 0 on success, and a non-zero value other‐
189       wise.
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AUTHOR

192       Maintained by the LLVM Team (https://llvm.org/).
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195       2003-2023, LLVM Project
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20015                                2023-01-12          LLVM-REMARK-SIZE-DIFF(1)
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