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Auto merge of #66631 - michaelwoerister:additional-pgo-tests, r=alexcrichton
Add additional regression tests for PGO This PR adds regression tests for making sure that - instrumentation records the right counts for branches taken and functions called, and that - the indirect call promotion pass actually is able to promote indirect calls. r? @alexcrichton
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‎src/test/run-make-fulldeps/pgo-branch-weights/Makefile

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# needs-profiler-support
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-include ../tools.mk
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# This test makes sure that instrumented binaries record the right counts for
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# functions being called and branches being taken. We run an instrumented binary
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# with an argument that causes a know path through the program and then check
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# that the expected counts get added to the use-phase LLVM IR.
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# LLVM doesn't support instrumenting binaries that use SEH:
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# https://github.com/rust-lang/rust/issues/61002
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#
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# Things work fine with -Cpanic=abort though.
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ifdef IS_MSVC
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COMMON_FLAGS=-Cpanic=abort
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endif
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all:
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# We don't compile `opaque` with either optimizations or instrumentation.
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# We don't compile `opaque` with either optimizations or instrumentation.
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$(RUSTC) $(COMMON_FLAGS) opaque.rs
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# Compile the test program with instrumentation
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mkdir -p "$(TMPDIR)"/prof_data_dir
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$(RUSTC) $(COMMON_FLAGS) interesting.rs \
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-Cprofile-generate="$(TMPDIR)"/prof_data_dir -O -Ccodegen-units=1
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$(RUSTC) $(COMMON_FLAGS) main.rs -Cprofile-generate="$(TMPDIR)"/prof_data_dir -O
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# The argument below generates to the expected branch weights
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$(call RUN,main aaaaaaaaaaaa2bbbbbbbbbbbb2bbbbbbbbbbbbbbbbcc) || exit 1
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"$(LLVM_BIN_DIR)"/llvm-profdata merge \
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-o "$(TMPDIR)"/prof_data_dir/merged.profdata \
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"$(TMPDIR)"/prof_data_dir
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$(RUSTC) $(COMMON_FLAGS) interesting.rs \
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-Cprofile-use="$(TMPDIR)"/prof_data_dir/merged.profdata -O \
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-Ccodegen-units=1 --emit=llvm-ir
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cat "$(TMPDIR)"/interesting.ll | "$(LLVM_FILECHECK)" filecheck-patterns.txt

‎src/test/run-make-fulldeps/pgo-branch-weights/filecheck-patterns.txt

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# First, establish that certain !prof labels are attached to the expected
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# functions and branching instructions.
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CHECK: define void @function_called_twice(i32 %c) {{.*}} !prof [[function_called_twice_id:![0-9]+]] {
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CHECK: br i1 {{.*}}, label {{.*}}, label {{.*}}, !prof [[branch_weights0:![0-9]+]]
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CHECK: define void @function_called_42_times(i32 %c) {{.*}} !prof [[function_called_42_times_id:![0-9]+]] {
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CHECK: switch i32 %c, label {{.*}} [
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CHECK-NEXT: i32 97, label {{.*}}
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CHECK-NEXT: i32 98, label {{.*}}
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CHECK-NEXT: ], !prof [[branch_weights1:![0-9]+]]
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CHECK: define void @function_called_never(i32 {{.*}} !prof [[function_called_never_id:![0-9]+]] {
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# Now check that those !prof tags hold the expected counts
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CHECK: [[function_called_twice_id]] = !{!"function_entry_count", i64 2}
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CHECK: [[branch_weights0]] = !{!"branch_weights", i32 2, i32 0}
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CHECK: [[function_called_42_times_id]] = !{!"function_entry_count", i64 42}
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CHECK: [[branch_weights1]] = !{!"branch_weights", i32 2, i32 12, i32 28}
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CHECK: [[function_called_never_id]] = !{!"function_entry_count", i64 0}

‎src/test/run-make-fulldeps/pgo-branch-weights/interesting.rs

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#![crate_name="interesting"]
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#![crate_type="rlib"]
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extern crate opaque;
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#[no_mangle]
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#[inline(never)]
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pub fn function_called_twice(c: char) {
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if c == '2' {
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// This branch is taken twice
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opaque::f1();
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} else {
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// This branch is never taken
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opaque::f2();
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}
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}
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#[no_mangle]
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#[inline(never)]
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pub fn function_called_42_times(c: char) {
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if c == 'a' {
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// This branch is taken 12 times
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opaque::f1();
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} else {
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if c == 'b' {
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// This branch is taken 28 times
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opaque::f2();
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} else {
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// This branch is taken 2 times
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opaque::f3();
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}
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}
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}
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#[no_mangle]
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#[inline(never)]
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pub fn function_called_never(_: char) {
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opaque::f1();
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}

‎src/test/run-make-fulldeps/pgo-branch-weights/main.rs

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extern crate interesting;
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fn main() {
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let arg = std::env::args().skip(1).next().unwrap();
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for c in arg.chars() {
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if c == '2' {
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interesting::function_called_twice(c);
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} else {
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interesting::function_called_42_times(c);
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}
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if c == '0' {
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interesting::function_called_never(c);
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}
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}
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}

‎src/test/run-make-fulldeps/pgo-branch-weights/opaque.rs

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#![crate_name="opaque"]
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#![crate_type="rlib"]
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pub fn f1() {}
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pub fn f2() {}
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pub fn f3() {}

‎src/test/run-make-fulldeps/pgo-indirect-call-promotion/Makefile

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# needs-profiler-support
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-include ../tools.mk
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# This test makes sure that indirect call promotion is performed. The test
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# programs calls the same function a thousand times through a function pointer.
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# Only PGO data provides the information that it actually always is the same
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# function. We verify that the indirect call promotion pass inserts a check
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# whether it can make a direct call instead of the indirect call.
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# LLVM doesn't support instrumenting binaries that use SEH:
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# https://github.com/rust-lang/rust/issues/61002
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#
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# Things work fine with -Cpanic=abort though.
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ifdef IS_MSVC
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COMMON_FLAGS=-Cpanic=abort
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endif
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all:
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# We don't compile `opaque` with either optimizations or instrumentation.
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# We don't compile `opaque` with either optimizations or instrumentation.
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$(RUSTC) $(COMMON_FLAGS) opaque.rs
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# Compile the test program with instrumentation
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mkdir -p "$(TMPDIR)"/prof_data_dir
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$(RUSTC) $(COMMON_FLAGS) interesting.rs \
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-Cprofile-generate="$(TMPDIR)"/prof_data_dir -O -Ccodegen-units=1
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$(RUSTC) $(COMMON_FLAGS) main.rs -Cprofile-generate="$(TMPDIR)"/prof_data_dir -O
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# The argument below generates to the expected branch weights
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$(call RUN,main) || exit 1
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"$(LLVM_BIN_DIR)"/llvm-profdata merge \
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-o "$(TMPDIR)"/prof_data_dir/merged.profdata \
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"$(TMPDIR)"/prof_data_dir
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$(RUSTC) $(COMMON_FLAGS) interesting.rs \
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-Cprofile-use="$(TMPDIR)"/prof_data_dir/merged.profdata -O \
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-Ccodegen-units=1 --emit=llvm-ir
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cat "$(TMPDIR)"/interesting.ll | "$(LLVM_FILECHECK)" filecheck-patterns.txt

‎src/test/run-make-fulldeps/pgo-indirect-call-promotion/filecheck-patterns.txt

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CHECK: define void @call_a_bunch_of_functions({{.*}} {
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# Make sure that indirect call promotion inserted a check against the most
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# frequently called function.
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CHECK: %{{.*}} = icmp eq void ()* %{{.*}}, @function_called_always
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# Check that the call to `function_called_always` was inlined, so that we
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# directly call `opaque_f1` from the upstream crate.
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CHECK: call void @opaque_f1()
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# Same checks as above, repeated for the trait object case
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CHECK: define void @call_a_bunch_of_trait_methods({{.*}}
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CHECK: %{{.*}} = icmp eq void ({}*)* %{{.*}}, {{.*}} @foo
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CHECK: tail call void @opaque_f2()

‎src/test/run-make-fulldeps/pgo-indirect-call-promotion/interesting.rs

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#![crate_name="interesting"]
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#![crate_type="rlib"]
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extern crate opaque;
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#[no_mangle]
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pub fn function_called_always() {
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opaque::opaque_f1();
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}
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#[no_mangle]
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pub fn function_called_never() {
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opaque::opaque_f2();
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}
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#[no_mangle]
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pub fn call_a_bunch_of_functions(fns: &[fn()]) {
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// Indirect call promotion transforms the below into something like
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//
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// for f in fns {
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// if f == function_called_always {
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// function_called_always()
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// } else {
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// f();
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// }
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// }
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//
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// where `function_called_always` actually gets inlined too.
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for f in fns {
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f();
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}
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}
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pub trait Foo {
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fn foo(&self);
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}
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impl Foo for u32 {
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#[no_mangle]
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fn foo(&self) {
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opaque::opaque_f2();
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}
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}
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#[no_mangle]
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pub fn call_a_bunch_of_trait_methods(trait_objects: &[&dyn Foo]) {
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// Same as above, just with vtables in between
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for x in trait_objects {
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x.foo();
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}
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}

‎src/test/run-make-fulldeps/pgo-indirect-call-promotion/main.rs

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extern crate interesting;
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fn main() {
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// function pointer case
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let fns: Vec<_> = std::iter::repeat(interesting::function_called_always as fn())
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.take(1000)
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.collect();
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interesting::call_a_bunch_of_functions(&fns[..]);
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// Trait object case
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let trait_objects = vec![0u32; 1000];
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let trait_objects: Vec<_> = trait_objects.iter().map(|x| x as &dyn interesting::Foo).collect();
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interesting::call_a_bunch_of_trait_methods(&trait_objects[..]);
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}

‎src/test/run-make-fulldeps/pgo-indirect-call-promotion/opaque.rs

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#![crate_name="opaque"]
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#![crate_type="rlib"]
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#[no_mangle]
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pub fn opaque_f1() {}
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#[no_mangle]
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pub fn opaque_f2() {}

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