<div dir="ltr">Nadav,<div><br></div><div>Thanks for your help. I tried adding multiplication, but I'm still seeing 0s and 1s:</div><div><br></div><div><div>$ cat test.c </div><div>int main(){</div><div> int r = rand();</div><div> if (r > 1){</div><div> return r*8;</div><div> }</div><div> return r*86;</div><div>}</div><div><br></div><div>$ clang-3.6 -S -emit-llvm test.c -o test.bc</div><div><br></div><div>$ opt-3.6 -analyze -targetlibinfo -cost-model ./test.bc</div><div>Printing analysis 'Target Library Information':</div><div>Pass::print not implemented for pass: 'Target Library Information'!</div><div>Printing analysis 'Cost Model Analysis' for function 'main':</div><div>Cost Model: Unknown cost for instruction: %1 = alloca i32, align 4</div><div>Cost Model: Unknown cost for instruction: %r = alloca i32, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 0, i32* %1</div><div>Cost Model: Unknown cost for instruction: %2 = call i32 (...)* @rand()</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %2, i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %3 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %4 = icmp sgt i32 %3, 1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br i1 %4, label %5, label %8</div><div>Cost Model: Found an estimated cost of 1 for instruction: %6 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %7 = mul nsw i32 %6, 8</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %7, i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br label %11</div><div>Cost Model: Found an estimated cost of 1 for instruction: %9 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %10 = mul nsw i32 %9, 86</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %10, i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br label %11</div><div>Cost Model: Found an estimated cost of 1 for instruction: %12 = load i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: ret i32 %12</div></div><div><br></div><div><br></div><div>I also tried adding setting the target with the flags you specified, but that didn't seem to change anything:</div><div><br></div><div><div>$ opt-3.6 -analyze -mcpu=core-avx2 -mtriple=x86_64-apple-darwin -targetlibinfo -cost-model ./test.bc</div><div>Printing analysis 'Target Library Information':</div><div>Pass::print not implemented for pass: 'Target Library Information'!</div><div>Printing analysis 'Cost Model Analysis' for function 'main':</div><div>Cost Model: Unknown cost for instruction: %1 = alloca i32, align 4</div><div>Cost Model: Unknown cost for instruction: %r = alloca i32, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 0, i32* %1</div><div>Cost Model: Unknown cost for instruction: %2 = call i32 (...)* @rand()</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %2, i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %3 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %4 = icmp sgt i32 %3, 1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br i1 %4, label %5, label %8</div><div>Cost Model: Found an estimated cost of 1 for instruction: %6 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %7 = mul nsw i32 %6, 8</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %7, i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br label %11</div><div>Cost Model: Found an estimated cost of 1 for instruction: %9 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %10 = mul nsw i32 %9, 86</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %10, i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br label %11</div><div>Cost Model: Found an estimated cost of 1 for instruction: %12 = load i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: ret i32 %12</div></div><div><br></div><div><br></div><div>Any other ideas?</div><div><br></div><div><br></div><div>Thanks,</div><div>Steve</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Aug 5, 2015 at 1:10 PM, Nadav Rotem <span dir="ltr"><<a href="mailto:nrotem@apple.com" target="_blank">nrotem@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><br><div><div><div class="h5"><blockquote type="cite"><div>On Aug 5, 2015, at 7:54 AM, Stephen Thomas <<a href="mailto:stephen.warner.thomas@gmail.com" target="_blank">stephen.warner.thomas@gmail.com</a>> wrote:</div><br><div><div dir="ltr"><span style="font-size:12.8000001907349px">Sorry if double posted... might have sent this to old mailing list address...<br></span><br><div class="gmail_quote">---------- Forwarded message ----------<br>From: <b class="gmail_sendername">Stephen Thomas</b> <span dir="ltr"><<a href="mailto:stephen.warner.thomas@gmail.com" target="_blank">stephen.warner.thomas@gmail.com</a>></span><br>Date: Wed, Aug 5, 2015 at 10:39 AM<br>Subject: How to use CostModel?<br>To: LLVM Dev <<a href="mailto:llvmdev@cs.uiuc.edu" target="_blank">llvmdev@cs.uiuc.edu</a>><br><br><br><div dir="ltr">Hi,<div><br></div><div>I'm trying to use the built-in CostModel class to estimate the number of machine instructions for each IR Instruction. To get a feel for what kind of output the CostModel pass gives, I ran it on the command line like so:</div><div><br></div><div><div>$ cat test.c </div><div>int main(){</div><div> int r = rand();</div><div> if (r > 1){</div><div> return ++r;</div><div> }</div><div> return r*86;</div><div>}</div><div><br></div><div>$ clang-3.6 -S -emit-llvm test.c -o test.bc</div><div><br></div><div>$ opt-3.6 -analyze -targetlibinfo -cost-model ./test.bc</div><div>Printing analysis 'Target Library Information':</div><div>Pass::print not implemented for pass: 'Target Library Information'!</div><div>Printing analysis 'Cost Model Analysis' for function 'main':</div><div>Cost Model: Unknown cost for instruction: %1 = alloca i32, align 4</div><div>Cost Model: Unknown cost for instruction: %r = alloca i32, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 0, i32* %1</div><div>Cost Model: Unknown cost for instruction: %2 = call i32 (...)* @rand()</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %2, i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %3 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %4 = icmp sgt i32 %3, 1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br i1 %4, label %5, label %8</div><div>Cost Model: Found an estimated cost of 1 for instruction: %6 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %7 = add nsw i32 %6, 1</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %7, i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %7, i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br label %11</div><div>Cost Model: Found an estimated cost of 1 for instruction: %9 = load i32* %r, align 4</div><div>Cost Model: Found an estimated cost of 1 for instruction: %10 = mul nsw i32 %9, 86</div><div>Cost Model: Found an estimated cost of 1 for instruction: store i32 %10, i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: br label %11</div><div>Cost Model: Found an estimated cost of 1 for instruction: %12 = load i32* %1</div><div>Cost Model: Found an estimated cost of 0 for instruction: ret i32 %12</div></div><div><br></div></div></div></div></div></blockquote><blockquote type="cite"><div><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div><br></div><div>Is it expected to only have 1s and 0s output?</div></div></div></div></div></blockquote><div><br></div></div></div><div>The output looks correct. Try adding multiplication and division and you'll see higher costs. </div><span class=""><br><blockquote type="cite"><div><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div> Also, what target architecture is being used for the estimations? (Is it auto detecting the architecture I'm on?)<br></div></div></div></div></div></blockquote><div><br></div></span><div>When the cost model analysis uses it uses the target that the compiler driver sets. In your experiments with OPT you can request a specific target using the -mcpu and -mtriple flags. Like this:</div><div><br></div><div>-mcpu=core-avx2 -mtriple=x86_64-apple-darwin </div><div><br></div><div>You can find more examples under llvm/test/Analysis/CostModel.</div><div><br></div><div>-Nadav</div><br><blockquote type="cite"><div><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div><br></div><div><br></div><div>Thanks,</div><div>Steve</div></div>
</div><br></div>
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