From d02c3b35b2f627fd3c06a1f6b3844c3abbc6c338 Mon Sep 17 00:00:00 2001
From: Jiahan Xie <765130715@qq.com>
Date: Thu, 31 Aug 2023 18:46:24 -0400
Subject: [PATCH 1/2] bril program for finding the majority element

---
 benchmarks/mem/major_elm.bril | 73 +++++++++++++++++++++++++++++++++++
 benchmarks/mem/major_elm.out  |  1 +
 benchmarks/mem/major_elm.prof |  1 +
 3 files changed, 75 insertions(+)
 create mode 100644 benchmarks/mem/major_elm.bril
 create mode 100644 benchmarks/mem/major_elm.out
 create mode 100644 benchmarks/mem/major_elm.prof

diff --git a/benchmarks/mem/major_elm.bril b/benchmarks/mem/major_elm.bril
new file mode 100644
index 000000000..53ca810ab
--- /dev/null
+++ b/benchmarks/mem/major_elm.bril
@@ -0,0 +1,73 @@
+# Return the majority element (appears more than floor(n/2) times) of an array, assuming that the majority element is guaranteed to exist.
+# Inputs: an array of size 3 (fixed);
+# Output: the majority element of the array.
+# Not a big example in terms of the array size and the total dynamic instructions; but I found Boyer-Moore voting algorithm very interesting!
+# Acknowledgement: brought idea from the pack function in Pat-Lafon's binary-search.bril to my create_arr.
+@main() {
+  arr_size: int = const 3;
+  e1: int = const 3;
+  e2: int = const 2;
+  e3: int = const 3;
+  nums: ptr<int> = call @create_arr arr_size e1 e2 e3;
+
+  zero: int = const 0;
+  one: int = const 1;
+  first_elm_ptr: ptr<int> = ptradd nums zero;
+  major_elm: int = load first_elm_ptr;
+  count: int = const 1;
+
+  i: int = const 1;
+  .check_bound:
+    end_cond: bool = ge i arr_size;
+    br end_cond .end .body;
+  
+  .body:
+    cur_ptr: ptr<int> = ptradd nums i;
+    cur_val: int = load cur_ptr;
+    cur_major_cond: bool = eq cur_val major_elm;
+    br cur_major_cond .incr_count .body.else;
+  
+  .incr_count:
+    count: int = add count one;
+    i: int = add i one;
+    jmp .check_bound;
+  
+  .body.else:
+    cnt_eq_0: bool = eq count zero;
+    br cnt_eq_0 .eq_zero_if .eq_zero_else;
+  
+  .eq_zero_if:
+    cur_ptr: ptr<int> = ptradd nums i;
+    major_elm: int = load cur_ptr;
+    count: int = add count one;
+    i: int = add i one;
+    jmp .check_bound;
+  
+  .eq_zero_else:
+    count: int = sub count one;
+    i: int = add i one;
+    jmp .check_bound;
+
+  .end:
+    free nums;
+    print major_elm;
+}
+
+@create_arr(size: int, e1: int, e2: int, e3: int): ptr<int> {
+  one: int = const 1;
+  i: int = const 0;
+  array: ptr<int> = alloc size;
+
+  loc: ptr<int> = ptradd array i;
+  store loc e1;
+
+  i: int = add i one;
+  loc: ptr<int> = ptradd array i;
+  store loc e2;
+
+  i: int = add i one;
+  loc: ptr<int> = ptradd array i;
+  store loc e3;
+
+  ret array;
+}
diff --git a/benchmarks/mem/major_elm.out b/benchmarks/mem/major_elm.out
new file mode 100644
index 000000000..00750edc0
--- /dev/null
+++ b/benchmarks/mem/major_elm.out
@@ -0,0 +1 @@
+3
diff --git a/benchmarks/mem/major_elm.prof b/benchmarks/mem/major_elm.prof
new file mode 100644
index 000000000..3ccbf1820
--- /dev/null
+++ b/benchmarks/mem/major_elm.prof
@@ -0,0 +1 @@
+total_dyn_inst: 47

From 262ea101adf94691d76c9a2a34fd07b0fff13af5 Mon Sep 17 00:00:00 2001
From: Jiahan Xie <765130715@qq.com>
Date: Thu, 31 Aug 2023 18:55:18 -0400
Subject: [PATCH 2/2] replace underscore with dash for my bril program's name,
 to be coherent with others; mention major-elm in the docs

---
 benchmarks/mem/{major_elm.bril => major-elm.bril} | 0
 benchmarks/mem/{major_elm.out => major-elm.out}   | 0
 benchmarks/mem/{major_elm.prof => major-elm.prof} | 0
 docs/tools/bench.md                               | 1 +
 4 files changed, 1 insertion(+)
 rename benchmarks/mem/{major_elm.bril => major-elm.bril} (100%)
 rename benchmarks/mem/{major_elm.out => major-elm.out} (100%)
 rename benchmarks/mem/{major_elm.prof => major-elm.prof} (100%)

diff --git a/benchmarks/mem/major_elm.bril b/benchmarks/mem/major-elm.bril
similarity index 100%
rename from benchmarks/mem/major_elm.bril
rename to benchmarks/mem/major-elm.bril
diff --git a/benchmarks/mem/major_elm.out b/benchmarks/mem/major-elm.out
similarity index 100%
rename from benchmarks/mem/major_elm.out
rename to benchmarks/mem/major-elm.out
diff --git a/benchmarks/mem/major_elm.prof b/benchmarks/mem/major-elm.prof
similarity index 100%
rename from benchmarks/mem/major_elm.prof
rename to benchmarks/mem/major-elm.prof
diff --git a/docs/tools/bench.md b/docs/tools/bench.md
index bbce89d1f..73fb1927e 100644
--- a/docs/tools/bench.md
+++ b/docs/tools/bench.md
@@ -34,6 +34,7 @@ The current benchmarks are:
 * `gcd`: Calculate Greatest Common Divisor (GCD) of two input positive integer using [Euclidean algorithm][euclidean_into].
 * `hanoi`: Print the solution to the *n*-disk [Tower of Hanoi][hanoi] puzzle.
 * `loopfact`: Compute *n!* imperatively using a loop.
+* `major-elm`: Find the majority element in an array using [a linear time voting algorithm](https://www.cs.utexas.edu/~moore/best-ideas/mjrty/).
 * `mandelbrot`: Generates a really low resolution, ascii, [mandelbrot set][mandelbrot].
 * `mat-inv` : Calculates the inverse of a 3x3 matrix and prints it out.
 * `mat-mul`: Multiplies two `nxn` matrices using the [naive][matmul] matrix multiplication algorithm. The matrices are randomly generated using a [linear congruential generator][rng].