[llvm] 49ab3b1 - [FuncSpec] Statistics

[Sjoerd Meijer via llvm-commits]

Author: Sjoerd Meijer
Date: 2021-06-16T09:11:51+01:00
New Revision: 49ab3b1735b66d48940a08a5daaa6398e98754ea

URL: https://github.com/llvm/llvm-project/commit/49ab3b1735b66d48940a08a5daaa6398e98754ea
DIFF: https://github.com/llvm/llvm-project/commit/49ab3b1735b66d48940a08a5daaa6398e98754ea.diff

LOG: [FuncSpec] Statistics

Adds some bookkeeping for collecting the number of specialised functions and a
test for that.

Differential Revision: https://reviews.llvm.org/D104102

Added: 
    llvm/test/Transforms/FunctionSpecialization/function-specialization-stats.ll

Modified: 
    llvm/lib/Transforms/IPO/FunctionSpecialization.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp b/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
index 4f4d55e82fd3b..2c381b7c1ef46 100644
--- a/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
@@ -41,7 +41,7 @@ using namespace llvm;
 
 #define DEBUG_TYPE "function-specialization"
 
-STATISTIC(NumFuncSpecialized, "Number of Functions Specialized");
+STATISTIC(NumFuncSpecialized, "Number of functions specialized");
 
 static cl::opt<bool> ForceFunctionSpecialization(
     "force-function-specialization", cl::init(false), cl::Hidden,
@@ -121,6 +121,8 @@ class FunctionSpecializer {
           LLVM_DEBUG(dbgs() << "FnSpecialization: Replaced constant argument: "
                             << Arg.getName() << "\n");
     }
+
+    NumFuncSpecialized += NbFunctionsSpecialized;
     return Changed;
   }
 
@@ -142,6 +144,10 @@ class FunctionSpecializer {
   }
 
 private:
+  // The number of functions specialised, used for collecting statistics and
+  // also in the cost model.
+  unsigned NbFunctionsSpecialized = 0;
+
   /// This function decides whether to specialize function \p F based on the
   /// known constant values its arguments can take on. Specialization is
   /// performed on the first interesting argument. Specializations based on
@@ -218,7 +224,7 @@ class FunctionSpecializer {
 
         // Mark all the specialized functions
         Specializations.push_back(Clone);
-        NumFuncSpecialized++;
+        NbFunctionsSpecialized++;
       }
 
       // TODO: if we want to support specialize specialized functions, and if
@@ -248,7 +254,7 @@ class FunctionSpecializer {
 
     // Otherwise, set the specialization cost to be the cost of all the
     // instructions in the function and penalty for specializing more functions.
-    unsigned Penalty = NumFuncSpecialized + 1;
+    unsigned Penalty = NbFunctionsSpecialized + 1;
     return Metrics.NumInsts * InlineConstants::InstrCost * Penalty;
   }
 
@@ -632,6 +638,5 @@ bool llvm::runFunctionSpecialization(
 
   // Clean up the IR by removing ssa_copy intrinsics.
   cleanup(M);
-
   return Changed;
 }

diff  --git a/llvm/test/Transforms/FunctionSpecialization/function-specialization-stats.ll b/llvm/test/Transforms/FunctionSpecialization/function-specialization-stats.ll
new file mode 100644
index 0000000000000..ca9d4c3025412
--- /dev/null
+++ b/llvm/test/Transforms/FunctionSpecialization/function-specialization-stats.ll
@@ -0,0 +1,45 @@
+; REQUIRES: asserts
+
+; RUN: opt -stats -function-specialization -deadargelim -inline -S < %s 2>&1 | FileCheck %s
+
+; CHECK: 2 deadargelim             - Number of unread args removed
+; CHECK: 1 deadargelim             - Number of unused return values removed
+; CHECK: 2 function-specialization - Number of functions specialized
+; CHECK: 4 inline                  - Number of functions deleted because all callers found
+; CHECK: 4 inline                  - Number of functions inlined
+; CHECK: 6 inline-cost             - Number of call sites analyzed
+
+define i64 @main(i64 %x, i1 %flag) {
+entry:
+  br i1 %flag, label %plus, label %minus
+
+plus:
+  %tmp0 = call i64 @compute(i64 %x, i64 (i64)* @plus)
+  br label %merge
+
+minus:
+  %tmp1 = call i64 @compute(i64 %x, i64 (i64)* @minus)
+  br label %merge
+
+merge:
+  %tmp2 = phi i64 [ %tmp0, %plus ], [ %tmp1, %minus]
+  ret i64 %tmp2
+}
+
+define internal i64 @compute(i64 %x, i64 (i64)* %binop) {
+entry:
+  %tmp0 = call i64 %binop(i64 %x)
+  ret i64 %tmp0
+}
+
+define internal i64 @plus(i64 %x) {
+entry:
+  %tmp0 = add i64 %x, 1
+  ret i64 %tmp0
+}
+
+define internal i64 @minus(i64 %x) {
+entry:
+  %tmp0 = sub i64 %x, 1
+  ret i64 %tmp0
+}