[llvm] df07121 - [hwasan][NFCI] Rename ClRandomSkipRate to ClRandomKeepRate (#126990)

[via llvm-commits]

Author: Thurston Dang
Date: 2025-02-12T18:43:00-08:00
New Revision: df07121d54432175ffc211d4165bfe7090c58c5e

URL: https://github.com/llvm/llvm-project/commit/df07121d54432175ffc211d4165bfe7090c58c5e
DIFF: https://github.com/llvm/llvm-project/commit/df07121d54432175ffc211d4165bfe7090c58c5e.diff

LOG: [hwasan][NFCI] Rename ClRandomSkipRate to ClRandomKeepRate (#126990)

The meaning of ClRandomSkipRate was inverted in
https://github.com/llvm/llvm-project/pull/88070 but the variable name
was not changed. This patch fixes it to avoid confusion.

Additionally, it elaborates the flag description to mention the
interaction between the random keep rate and hotness cutoff.

Added: 
    

Modified: 
    llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 645c102752692..a3423912d4f31 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -195,9 +195,12 @@ static cl::opt<int> ClHotPercentileCutoff("hwasan-percentile-cutoff-hot",
                                           cl::desc("Hot percentile cutoff."));
 
 static cl::opt<float>
-    ClRandomSkipRate("hwasan-random-rate",
+    ClRandomKeepRate("hwasan-random-rate",
                      cl::desc("Probability value in the range [0.0, 1.0] "
-                              "to keep instrumentation of a function."));
+                              "to keep instrumentation of a function. "
+                              "Note: instrumentation can be skipped randomly "
+                              "OR because of the hot percentile cutoff, if "
+                              "both are supplied."));
 
 STATISTIC(NumTotalFuncs, "Number of total funcs");
 STATISTIC(NumInstrumentedFuncs, "Number of instrumented funcs");
@@ -301,7 +304,7 @@ class HWAddressSanitizer {
       : M(M), SSI(SSI) {
     this->Recover = optOr(ClRecover, Recover);
     this->CompileKernel = optOr(ClEnableKhwasan, CompileKernel);
-    this->Rng = ClRandomSkipRate.getNumOccurrences() ? M.createRNG(DEBUG_TYPE)
+    this->Rng = ClRandomKeepRate.getNumOccurrences() ? M.createRNG(DEBUG_TYPE)
                                                      : nullptr;
 
     initializeModule();
@@ -1599,9 +1602,9 @@ bool HWAddressSanitizer::selectiveInstrumentationShouldSkip(
   };
 
   auto SkipRandom = [&]() {
-    if (!ClRandomSkipRate.getNumOccurrences())
+    if (!ClRandomKeepRate.getNumOccurrences())
       return false;
-    std::bernoulli_distribution D(ClRandomSkipRate);
+    std::bernoulli_distribution D(ClRandomKeepRate);
     return !D(*Rng);
   };