[Coverage] Support for C++17 if initializers

[vsk]

Summary

Generate coverage mappings for <init> in if (<init>; <cond>).

Here's some sample output (let's hope phab gets the spaces right :) --

12|       |// CHECK-LABEL: define {{.*}}void @_Z11switch_initv()
13|       |// PGOGEN: store {{.*}} @[[SIC]], i64 0, i64 0
14|      1|void switch_init() {
15|      1|  switch (int i = true ? 0 : 1; i) {}
                                    ^1  ^0
16|      1|  // PGOGEN: store {{.*}} @[[SIC]], i64 0, i64 2
17|      1|  // PGOGEN: store {{.*}} @[[SIC]], i64 0, i64 1
18|      1|}
19|       |
20|       |// Note: We expect counters for the function entry block, the condition in the
21|       |// if initializer, and the if successor block.
22|       |//
23|       |// CHECK-LABEL: define {{.*}}void @_Z7if_initv()
24|       |// PGOGEN: store {{.*}} @[[IIC]], i64 0, i64 0
25|      1|void if_init() {
26|      1|  if (int i = true ? 0 : 1; i) {}
                                ^1  ^0 ^1 ^0
27|      1|  // PGOGEN: store {{.*}} @[[IIC]], i64 0, i64 2
28|      1|  // PGOGEN: store {{.*}} @[[IIC]], i64 0, i64 1
29|      1|}

I did some local testing of this patch (as well as D25539) using a maze of macros to generate parts of the IfStmt / SwitchStmt. The goal of that exercise was to break popRegions(). Ultimately I decided against checking those tests in because they seem a bit paranoid. We're not actually pushing new regions for the initializer statements..

[ikudrin]

LGTM.

lib/CodeGen/CodeGenPGO.cpp

void VisitSwitchCase(const SwitchCase *S) {
     CountMap[S] = CaseCount;
     RecordNextStmtCount = true;
     Visit(S->getSubStmt());
   }
 
   void VisitIfStmt(const IfStmt *S) {
     RecordStmtCount(S);
     uint64_t ParentCount = CurrentCount;
+    if (S->getInit())
+      Visit(S->getInit());
     Visit(S->getCond());
 
     // Counter tracks the "then" part of an if statement. The count for
     // the "else" part, if it exists, will be calculated from this counter.
     uint64_t ThenCount = setCount(PGO.getRegionCount(S));
     CountMap[S->getThen()] = ThenCount;
     Visit(S->getThen());
     uint64_t OutCount = CurrentCount;

lib/CodeGen/CoverageMappingGen.cpp

       if (const Expr *RHS = CS->getRHS())
         Visit(RHS);
     }
     Visit(S->getSubStmt());
   }
 
   void VisitIfStmt(const IfStmt *S) {
     extendRegion(S);
+    if (S->getInit())
+      Visit(S->getInit());
+
     // Extend into the condition before we propagate through it below - this is
     // needed to handle macros that generate the "if" but not the condition.
     extendRegion(S->getCond());
 
     Counter ParentCount = getRegion().getCounter();
     Counter ThenCount = getRegionCounter(S);
 
     // Emitting a counter for the condition makes it easier to interpret the

test/CoverageMapping/if.cpp

-// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name if.c %s | FileCheck %s
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -std=c++1z -triple %itanium_abi_triple -main-file-name if.cpp %s | FileCheck %s
 
+int nop() { return 0; }
+
+// CHECK-LABEL: _Z3foov:
+void foo() {                    // CHECK-NEXT: [[@LINE]]:12 -> [[@LINE+5]]:2 = #0
+  if (int j = true ? nop()      // CHECK-NEXT: [[@LINE]]:22 -> [[@LINE]]:27 = #2
+                   : nop();     // CHECK-NEXT: [[@LINE]]:22 -> [[@LINE]]:27 = (#0 - #2)
+      j)                        // CHECK-NEXT: [[@LINE]]:7 -> [[@LINE]]:8 = #0
+    ++j;                        // CHECK-NEXT: [[@LINE]]:5 -> [[@LINE]]:8 = #1
+}
+
+// CHECK-LABEL: main:
 int main() {                    // CHECK: File 0, [[@LINE]]:12 -> {{[0-9]+}}:2 = #0
   int i = 0;
                                 // CHECK-NEXT: File 0, [[@LINE+1]]:6 -> [[@LINE+1]]:12 = #0
   if(i == 0) i = 1;             // CHECK-NEXT: File 0, [[@LINE]]:14 -> [[@LINE]]:19 = #1
                                 // CHECK-NEXT: File 0, [[@LINE+1]]:6 -> [[@LINE+1]]:12 = #0
   if(i == 1)
     i = 2;                      // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE]]:10 = #2
                                 // CHECK-NEXT: File 0, [[@LINE+1]]:6 -> [[@LINE+1]]:12 = #0

test/Profile/cxx-stmt-initializers.cpp

 // Tests for instrumentation of C++17 statement initializers
 
 // RUN: %clang_cc1 -x c++ %s -triple %itanium_abi_triple -main-file-name cxx-stmt-initializers.cpp -std=c++1z -o - -emit-llvm -fprofile-instrument=clang > %tgen
 // RUN: FileCheck --input-file=%tgen -check-prefix=CHECK -check-prefix=PGOGEN %s
 
 // PGOGEN: @[[SIC:__profc__Z11switch_initv]] = private global [3 x i64] zeroinitializer
+// PGOGEN: @[[IIC:__profc__Z7if_initv]] = private global [3 x i64] zeroinitializer
 
 // Note: We expect counters for the function entry block, the condition in the
 // switch initializer, and the switch successor block.
 //
 // CHECK-LABEL: define {{.*}}void @_Z11switch_initv()
 // PGOGEN: store {{.*}} @[[SIC]], i64 0, i64 0
 void switch_init() {
   switch (int i = true ? 0 : 1; i) {}
   // PGOGEN: store {{.*}} @[[SIC]], i64 0, i64 2
   // PGOGEN: store {{.*}} @[[SIC]], i64 0, i64 1
 }
+
+// Note: We expect counters for the function entry block, the condition in the
+// if initializer, and the if successor block.
+//
+// CHECK-LABEL: define {{.*}}void @_Z7if_initv()
+// PGOGEN: store {{.*}} @[[IIC]], i64 0, i64 0
+void if_init() {
+  if (int i = true ? 0 : 1; i) {}
+  // PGOGEN: store {{.*}} @[[IIC]], i64 0, i64 2
+  // PGOGEN: store {{.*}} @[[IIC]], i64 0, i64 1
+}