[compiler-rt] [compiler-rt][nsan] Add support for nan detection (PR #101531)

[Alexander Shaposhnikov via llvm-commits]

================
@@ -0,0 +1,54 @@
+// RUN: %clangxx_nsan -O0 -g -DSOFTMAX=softmax %s -o %t
+// RUN: NSAN_OPTIONS=check_nan=true,halt_on_error=0,log2_max_relative_error=19 %run %t 2>&1 | FileCheck %s
+
+// RUN: %clangxx_nsan -O3 -g -DSOFTMAX=softmax %s -o %t
+// RUN: NSAN_OPTIONS=check_nan=true,halt_on_error=0,log2_max_relative_error=19 %run %t 2>&1 | FileCheck %s
+
+// RUN: %clangxx_nsan -O0 -g -DSOFTMAX=stable_softmax %s -o %t
+// RUN: NSAN_OPTIONS=check_nan=true,halt_on_error=1,log2_max_relative_error=19 %run %t 
+
+// RUN: %clangxx_nsan -O3 -g -DSOFTMAX=stable_softmax %s -o %t
+// RUN: NSAN_OPTIONS=check_nan=true,halt_on_error=1,log2_max_relative_error=19 %run %t
+
+#include<iostream>
+#include<vector>
+#include<algorithm>
+#include<cmath>
+
+// unstable softmax
+template <typename T>
+__attribute__((noinline)) void softmax(std::vector<T> &values) {
+    T sum_exp = 0.0;
+    for (auto &i: values) {
+      i = std::exp(i);
+      sum_exp += i;
+    }
+    for (auto &i: values) {
+      i /= sum_exp;
+    }
+}
+
+// use max value to avoid overflow
+// \sigma_i exp(x_i) / \sum_j exp(x_j) = \sigma_i exp(x_i - max(x)) / \sum_j exp(x_j - max(x))
+template <typename T>
+__attribute__((noinline)) void stable_softmax(std::vector<T> values) {
----------------
alexander-shaposhnikov wrote:

missing ref: &values

https://github.com/llvm/llvm-project/pull/101531