b034905c82
When we collect a contextual profile, we sample the threads entering its root and only collect on one at a time (see `ContextRoot::Taken`). If we want to compare profiles between contextual profiles, and/or flat profiles, we have a problem: we don't know how to compare the counter values relative to each other. To that end, we add `ContextRoot::TotalEntries`, which is incremented every time a root is entered and serves as multiplier for the counter values collected under that root. We expose this in the profile and leave the normalization to the user of the profile, for a few reasons: * it's only needed if reasoning about all profiles in aggregate. * the goal, in compiler_rt, is to flush out the profile as quickly as possible, and performing multiplications adds an overhead that may not even be necessary if the consumer of the profile doesn't care about combining profiles * the information itself may be interesting as an indication of relative sampling of various contexts.
86 lines
3.0 KiB
LLVM
86 lines
3.0 KiB
LLVM
; Check that we handle `step` instrumentations. These addorn `select`s.
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; We don't want to confuse the `step` with normal increments, the latter of which
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; we use for BB ID-ing: we want to keep the `step`s after inlining, except if
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; the `select` is elided.
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;
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; RUN: split-file %s %t
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; RUN: llvm-ctxprof-util fromYAML --input=%t/profile.yaml --output=%t/profile.ctxprofdata
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;
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; RUN: opt -passes=ctx-instr-gen %t/example.ll -use-ctx-profile=%t/profile.ctxprofdata -S -o - | FileCheck %s --check-prefix=INSTR
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; RUN: opt -passes=ctx-instr-gen,module-inline %t/example.ll -use-ctx-profile=%t/profile.ctxprofdata -S -o - | FileCheck %s --check-prefix=POST-INL
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; RUN: opt -passes=ctx-instr-gen,module-inline,ctx-prof-flatten %t/example.ll -use-ctx-profile=%t/profile.ctxprofdata -S -o - | FileCheck %s --check-prefix=FLATTEN
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; INSTR-LABEL: yes:
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; INSTR-NEXT: call void @llvm.instrprof.increment(ptr @foo, i64 [[#]], i32 2, i32 1)
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; INSTR-NEXT: call void @llvm.instrprof.callsite(ptr @foo, i64 [[#]], i32 2, i32 0, ptr @bar)
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; INSTR-LABEL: no:
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; INSTR-NEXT: call void @llvm.instrprof.callsite(ptr @foo, i64 [[#]], i32 2, i32 1, ptr @bar)
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; INSTR-LABEL: define i32 @bar
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; INSTR-NEXT: call void @llvm.instrprof.increment(ptr @bar, i64 [[#]], i32 2, i32 0)
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; INSTR-NEXT: %inc =
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; INSTR: %test = icmp eq i32 %t, 0
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; INSTR-NEXT: %1 = zext i1 %test to i64
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; INSTR-NEXT: call void @llvm.instrprof.increment.step(ptr @bar, i64 [[#]], i32 2, i32 1, i64 %1)
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; INSTR-NEXT: %res = select
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; POST-INL-LABEL: yes:
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; POST-INL-NEXT: call void @llvm.instrprof.increment
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; POST-INL: call void @llvm.instrprof.increment.step
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; POST-INL-NEXT: %res.i = select
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; POST-INL-LABEL: no:
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; POST-INL-NEXT: call void @llvm.instrprof.increment
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; POST-INL-NEXT: br label
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; POST-INL-LABEL: exit:
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; POST-INL-NEXT: %res = phi i32 [ %res.i, %yes ], [ 1, %no ]
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; FLATTEN-LABEL: yes:
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; FLATTEN: %res.i = select i1 %test.i, i32 %inc.i, i32 %dec.i, !prof ![[SELPROF:[0-9]+]]
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; FLATTEN-LABEL: no:
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;
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; See the profile, in the "yes" case we set the step counter's value, in @bar, to 3. The total
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; entry count of that BB is 4.
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; ![[SELPROF]] = !{!"branch_weights", i32 3, i32 1}
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;--- example.ll
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define i32 @foo(i32 %t) !guid !0 {
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%test = icmp slt i32 %t, 0
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br i1 %test, label %yes, label %no
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yes:
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%res1 = call i32 @bar(i32 %t) alwaysinline
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br label %exit
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no:
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; this will result in eliding the select in @bar, when inlined.
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%res2 = call i32 @bar(i32 0) alwaysinline
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br label %exit
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exit:
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%res = phi i32 [%res1, %yes], [%res2, %no]
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ret i32 %res
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}
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define i32 @bar(i32 %t) !guid !1 {
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%inc = add i32 %t, 1
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%dec = sub i32 %t, 1
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%test = icmp eq i32 %t, 0
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%res = select i1 %test, i32 %inc, i32 %dec
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ret i32 %res
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}
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!0 = !{i64 1234}
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!1 = !{i64 5678}
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;--- profile.yaml
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Contexts:
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- Guid: 1234
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TotalRootEntryCount: 100
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Counters: [10, 4]
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Callsites: -
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- Guid: 5678
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Counters: [4,3]
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-
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- Guid: 5678
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Counters: [6,6]
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