From b7718647049d4534ab9425a93565bc0fb8ff5d48 Mon Sep 17 00:00:00 2001
From: Jesse Michel <jmmichel@mit.edu>
Date: Thu, 2 Nov 2023 21:32:55 -0400
Subject: [PATCH 1/4] Ring of springs integration test using modulo

---
 enzyme/test/Integration/Sparse/ringspring.cpp | 116 ++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 enzyme/test/Integration/Sparse/ringspring.cpp

diff --git a/enzyme/test/Integration/Sparse/ringspring.cpp b/enzyme/test/Integration/Sparse/ringspring.cpp
new file mode 100644
index 000000000000..ad54ec94228f
--- /dev/null
+++ b/enzyme/test/Integration/Sparse/ringspring.cpp
@@ -0,0 +1,116 @@
+// This should work on LLVM 7, 8, 9, however in CI the version of clang installed on Ubuntu 18.04 cannot load
+// a clang plugin properly without segfaulting on exit. This is fine on Ubuntu 20.04 or later LLVM versions...
+// RUN: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O1 %s -S -emit-llvm -o - %loadClangEnzyme -mllvm -enzyme-auto-sparsity=1 | %lli - ; fi
+// RUN: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O2 %s -S -emit-llvm -o - %loadClangEnzyme -mllvm -enzyme-auto-sparsity=1  | %lli - ; fi
+// RUN: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O3 %s -S -emit-llvm -o - %loadClangEnzyme  -mllvm -enzyme-auto-sparsity=1 | %lli - ; fi
+// TODO: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O1 %s -S -emit-llvm -o - %newLoadClangEnzyme -mllvm -enzyme-auto-sparsity=1 -S | %lli - ; fi
+// TODO: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O2 %s -S -emit-llvm -o - %newLoadClangEnzyme -mllvm -enzyme-auto-sparsity=1 -S | %lli - ; fi
+// TODO: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O3 %s -S -emit-llvm -o - %newLoadClangEnzyme -mllvm -enzyme-auto-sparsity=1 -S | %lli - ; fi
+
+#include <stdio.h>
+#include <assert.h>
+#include <vector>
+
+#include<math.h>
+
+struct triple {
+    size_t row;
+    size_t col;
+    double val;
+    triple(triple&&) = default;
+    triple(size_t row, size_t col, double val) : row(row), col(col), val(val) {}
+};
+
+extern int enzyme_dup;
+extern int enzyme_dupnoneed;
+extern int enzyme_out;
+extern int enzyme_const;
+
+extern void __enzyme_autodiff(void *, ...);
+
+extern void __enzyme_fwddiff(void *, ...);
+
+extern double* __enzyme_todense(void *, ...) noexcept;
+
+
+/// Compute energy
+double f(size_t N, double* input) {
+    double out = 0;
+    __builtin_assume(!((N-1) == 0));
+    for (size_t i=0; i<N; i++) {
+        //double sub = input[i] - input[i+1]; 
+        // out += sub * sub;
+        double sub = input[(i + 1) % N] - input[i % N]; 
+        out += (sqrt(sub) + 1)*(sqrt(sub) + 1);
+    }
+    return out;
+}
+
+/// Perform dinput += gradient(f)
+void grad_f(size_t N, double* input, double* dinput) {
+    __enzyme_autodiff((void*)f, enzyme_const, N, enzyme_dup, input, dinput);
+}
+
+
+void ident_store(double , int64_t idx, size_t i) {
+    assert(0 && "should never load");
+}
+
+__attribute__((always_inline))
+double ident_load(int64_t idx, size_t i, size_t N) {
+    idx /= sizeof(double);
+    return (double)(idx == i);// ? 1.0 : 0.0;
+}
+
+__attribute__((enzyme_sparse_accumulate))
+void inner_store(int64_t row, int64_t col, double val, std::vector<triple> &triplets) {
+    printf("row=%d col=%d val=%f\n", row, col, val);
+    assert(abs(val) > 0.00001);
+    triplets.emplace_back(row, col, val);
+}
+
+__attribute__((always_inline))
+void sparse_store(double val, int64_t idx, size_t i, size_t N, std::vector<triple> &triplets) {
+    if (val == 0.0) return;
+    idx /= sizeof(double);
+    inner_store(i, idx, val, triplets);
+}
+
+__attribute__((always_inline))
+double sparse_load(int64_t idx, size_t i, size_t N, std::vector<triple> &triplets) {
+    return 0.0;
+}
+
+__attribute__((noinline))
+std::vector<triple> hess_f(size_t N, double* input) {
+    std::vector<triple> triplets;
+    __builtin_assume(N > 0);
+    for (size_t i=0; i<N; i++) {
+        __builtin_assume(i < 100000000);
+        double* d_input = __enzyme_todense((void*)ident_load, (void*)ident_store, i, N);
+        double* d_dinput = __enzyme_todense((void*)sparse_load, (void*)sparse_store, i, N, &triplets);
+
+       __enzyme_fwddiff((void*)grad_f, 
+                            enzyme_const, N,
+                            enzyme_dup, input, d_input,
+                            enzyme_dupnoneed, (double*)0x1, d_dinput);
+
+    }
+    return triplets;
+}
+
+int main() {
+  size_t N = 8;
+  double x[N];
+  for (int i=0; i<N; i++) x[i] = (i + 1) * (i + 1);
+
+  auto res = hess_f(N, &x[0]);
+
+
+  printf("%ld\n", res.size());
+
+  for (auto & tup : res)
+      printf("%ld, %ld = %f\n", tup.row, tup.col, tup.val);
+
+  return 0;
+}

From 70e5271958a57c415dc362e45902705b9223b32a Mon Sep 17 00:00:00 2001
From: Jesse Michel <jmmichel@mit.edu>
Date: Tue, 7 Nov 2023 16:32:39 -0500
Subject: [PATCH 2/4] new bugs

---
 enzyme/test/Integration/Sparse/ringspring.cpp | 36 ++++++++++++++-----
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/enzyme/test/Integration/Sparse/ringspring.cpp b/enzyme/test/Integration/Sparse/ringspring.cpp
index ad54ec94228f..7c020a23e7b5 100644
--- a/enzyme/test/Integration/Sparse/ringspring.cpp
+++ b/enzyme/test/Integration/Sparse/ringspring.cpp
@@ -7,10 +7,14 @@
 // TODO: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O2 %s -S -emit-llvm -o - %newLoadClangEnzyme -mllvm -enzyme-auto-sparsity=1 -S | %lli - ; fi
 // TODO: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O3 %s -S -emit-llvm -o - %newLoadClangEnzyme -mllvm -enzyme-auto-sparsity=1 -S | %lli - ; fi
 
+// everything should be always inline
+
+
 #include <stdio.h>
 #include <assert.h>
 #include <vector>
 
+
 #include<math.h>
 
 struct triple {
@@ -21,6 +25,9 @@ struct triple {
     triple(size_t row, size_t col, double val) : row(row), col(col), val(val) {}
 };
 
+
+size_t N = 8;
+
 extern int enzyme_dup;
 extern int enzyme_dupnoneed;
 extern int enzyme_out;
@@ -36,12 +43,12 @@ extern double* __enzyme_todense(void *, ...) noexcept;
 /// Compute energy
 double f(size_t N, double* input) {
     double out = 0;
-    __builtin_assume(!((N-1) == 0));
+    // __builtin_assume(!((N-1) == 0));
     for (size_t i=0; i<N; i++) {
         //double sub = input[i] - input[i+1]; 
         // out += sub * sub;
-        double sub = input[(i + 1) % N] - input[i % N]; 
-        out += (sqrt(sub) + 1)*(sqrt(sub) + 1);
+        double sub = (input[i+1] - input[i]) * (input[i+1] - input[i]);
+        out += (sqrt(sub) - 1)*(sqrt(sub) - 1);
     }
     return out;
 }
@@ -59,14 +66,14 @@ void ident_store(double , int64_t idx, size_t i) {
 __attribute__((always_inline))
 double ident_load(int64_t idx, size_t i, size_t N) {
     idx /= sizeof(double);
-    return (double)(idx == i);// ? 1.0 : 0.0;
+    return (double)(idx % N == i % N);// ? 1.0 : 0.0;
 }
 
 __attribute__((enzyme_sparse_accumulate))
 void inner_store(int64_t row, int64_t col, double val, std::vector<triple> &triplets) {
-    printf("row=%d col=%d val=%f\n", row, col, val);
-    assert(abs(val) > 0.00001);
-    triplets.emplace_back(row, col, val);
+    printf("row=%d col=%d val=%f\n", row, col % N, val);
+    // assert(abs(val) > 0.00001);
+    triplets.emplace_back(row % N, col % N, val);
 }
 
 __attribute__((always_inline))
@@ -81,9 +88,21 @@ double sparse_load(int64_t idx, size_t i, size_t N, std::vector<triple> &triplet
     return 0.0;
 }
 
+__attribute__((always_inline))
+void never_store(double val, int64_t idx, double* input, size_t N) {
+    assert(0 && "this is a read only input, why are you storing here...");
+}
+
+__attribute__((always_inline))
+double mod_load(int64_t idx, double* input, size_t N) {
+    idx /= sizeof(double);
+    return input[idx % N];
+}
+
 __attribute__((noinline))
 std::vector<triple> hess_f(size_t N, double* input) {
     std::vector<triple> triplets;
+    input = __enzyme_todense((void*)mod_load, (void*)never_store, input, N);
     __builtin_assume(N > 0);
     for (size_t i=0; i<N; i++) {
         __builtin_assume(i < 100000000);
@@ -99,8 +118,9 @@ std::vector<triple> hess_f(size_t N, double* input) {
     return triplets;
 }
 
+
 int main() {
-  size_t N = 8;
+  // size_t N = 8;
   double x[N];
   for (int i=0; i<N; i++) x[i] = (i + 1) * (i + 1);
 

From 59ce6557fe45585116ac15dc359c538aa2453156 Mon Sep 17 00:00:00 2001
From: "William S. Moses" <gh@wsmoses.com>
Date: Tue, 7 Nov 2023 23:54:20 -0500
Subject: [PATCH 3/4] add phi fix

---
 enzyme/Enzyme/FunctionUtils.cpp | 92 +++++++++++++++++----------------
 enzyme/Enzyme/GradientUtils.cpp | 49 +++++++++++++++---
 2 files changed, 89 insertions(+), 52 deletions(-)

diff --git a/enzyme/Enzyme/FunctionUtils.cpp b/enzyme/Enzyme/FunctionUtils.cpp
index 5abc0a3729f3..703e0d833a76 100644
--- a/enzyme/Enzyme/FunctionUtils.cpp
+++ b/enzyme/Enzyme/FunctionUtils.cpp
@@ -4329,56 +4329,58 @@ std::optional<std::string> fixSparse_inner(Instruction *cur, llvm::Function &F,
     }
     // phi (idx=0) ? b, a, a -> select (idx == 0), b, a
     if (auto L = LI.getLoopFor(PN->getParent()))
-      if (auto idx = L->getCanonicalInductionVariable())
-        if (auto PH = L->getLoopPreheader()) {
-          bool legal = idx != PN;
-          auto ph_idx = PN->getBasicBlockIndex(PH);
-          for (size_t i = 0; i < PN->getNumIncomingValues(); i++) {
-            if ((int)i == ph_idx)
-              continue;
-            auto v = PN->getIncomingValue(i);
-            if (v != PN->getIncomingValue(1 - ph_idx)) {
-              legal = false;
-              break;
-            }
-            // The given var must dominate the loop
-            if (isa<Constant>(v))
-              continue;
-            if (isa<Argument>(v))
-              continue;
-            // exception for the induction itself, which we handle specially
-            if (v == idx)
-              continue;
-            auto I = cast<Instruction>(v);
-            if (!DT.dominates(I, PN)) {
-              legal = false;
-              break;
-            }
-          }
-          if (legal) {
-            auto val = PN->getIncomingValue(1 - ph_idx);
-            push(val);
-            if (val == idx) {
-              val = pushcse(
-                  B.CreateSub(idx, ConstantInt::get(idx->getType(), 1)));
+      if (L->getHeader() == PN->getParent())
+        if (auto idx = L->getCanonicalInductionVariable())
+          if (auto PH = L->getLoopPreheader()) {
+            bool legal = idx != PN;
+            auto ph_idx = PN->getBasicBlockIndex(PH);
+            assert(ph_idx >= 0);
+            for (size_t i = 0; i < PN->getNumIncomingValues(); i++) {
+              if ((int)i == ph_idx)
+                continue;
+              auto v = PN->getIncomingValue(i);
+              if (v != PN->getIncomingValue(1 - ph_idx)) {
+                legal = false;
+                break;
+              }
+              // The given var must dominate the loop
+              if (isa<Constant>(v))
+                continue;
+              if (isa<Argument>(v))
+                continue;
+              // exception for the induction itself, which we handle specially
+              if (v == idx)
+                continue;
+              auto I = cast<Instruction>(v);
+              if (!DT.dominates(I, PN)) {
+                legal = false;
+                break;
+              }
             }
+            if (legal) {
+              auto val = PN->getIncomingValue(1 - ph_idx);
+              push(val);
+              if (val == idx) {
+                val = pushcse(
+                    B.CreateSub(idx, ConstantInt::get(idx->getType(), 1)));
+              }
 
-            auto val2 = PN->getIncomingValue(ph_idx);
-            push(val2);
+              auto val2 = PN->getIncomingValue(ph_idx);
+              push(val2);
 
-            auto c0 = ConstantInt::get(idx->getType(), 0);
-            // if (val2 == c0 && PN->getIncomingValue(1 - ph_idx) == idx) {
-            //  val = B.CreateBinaryIntrinsic(Intrinsic::umax, c0, val);
-            //} else {
-            auto eq = pushcse(B.CreateICmpEQ(idx, c0));
-            val = pushcse(
-                B.CreateSelect(eq, val2, val, "phisel." + cur->getName()));
-            //}
+              auto c0 = ConstantInt::get(idx->getType(), 0);
+              // if (val2 == c0 && PN->getIncomingValue(1 - ph_idx) == idx) {
+              //  val = B.CreateBinaryIntrinsic(Intrinsic::umax, c0, val);
+              //} else {
+              auto eq = pushcse(B.CreateICmpEQ(idx, c0));
+              val = pushcse(
+                  B.CreateSelect(eq, val2, val, "phisel." + cur->getName()));
+              //}
 
-            replaceAndErase(cur, val);
-            return "PhiLoop0Sel";
+              replaceAndErase(cur, val);
+              return "PhiLoop0Sel";
+            }
           }
-        }
     // phi (sitofp a), (sitofp b) -> sitofp (phi a, b)
     {
       SmallVector<Value *, 1> negOps;
diff --git a/enzyme/Enzyme/GradientUtils.cpp b/enzyme/Enzyme/GradientUtils.cpp
index ca5996eca9ce..d52a5f80f577 100644
--- a/enzyme/Enzyme/GradientUtils.cpp
+++ b/enzyme/Enzyme/GradientUtils.cpp
@@ -9158,14 +9158,15 @@ bool GradientUtils::needsCacheWholeAllocation(
     return false;
   if (!found->second)
     return true;
-  SmallVector<std::pair<const Instruction *, size_t>, 1> todo;
+  // User, operand of input, whehter the input is the original allocation
+  SmallVector<std::tuple<const Instruction *, size_t, bool>, 1> todo;
   for (auto &use : origInst->uses())
-    todo.push_back(
-        std::make_pair(cast<Instruction>(use.getUser()), use.getOperandNo()));
-  SmallSet<std::pair<const Instruction *, size_t>, 1> seen;
+    todo.push_back(std::make_tuple(cast<Instruction>(use.getUser()),
+                                   use.getOperandNo(), true));
+  SmallSet<std::tuple<const Instruction *, size_t, bool>, 1> seen;
   while (todo.size()) {
     auto pair = todo.back();
-    auto [cur, idx] = pair;
+    auto [cur, idx, orig] = pair;
     todo.pop_back();
     if (seen.count(pair))
       continue;
@@ -9184,6 +9185,8 @@ bool GradientUtils::needsCacheWholeAllocation(
           II->getIntrinsicID() == Intrinsic::masked_load)
         continue;
 
+    bool returnedSameValue = false;
+
     if (auto CI = dyn_cast<CallInst>(cur)) {
 #if LLVM_VERSION_MAJOR >= 14
       if (idx < CI->arg_size())
@@ -9193,6 +9196,36 @@ bool GradientUtils::needsCacheWholeAllocation(
       {
         if (isNoCapture(CI, idx))
           continue;
+
+        if (auto F = CI->getCalledFunction())
+          if (F->getCallingConv() == CI->getCallingConv()) {
+            bool onlyReturnUses = true;
+            bool hasReturnUse = true;
+
+            for (auto u : F->getArg(idx)->users()) {
+              if (isa<ReturnInst>(u)) {
+                hasReturnUse = true;
+                continue;
+              }
+              onlyReturnUses = false;
+              continue;
+            }
+            // The arg itself has no use in the function
+            if (onlyReturnUses && !hasReturnUse)
+              continue;
+
+            // If this is the original allocation, we return it guaranteed, and
+            // cache the return, that's still fine
+            if (onlyReturnUses && orig) {
+              found = knownRecomputeHeuristic.find(cur);
+              if (found == knownRecomputeHeuristic.end())
+                continue;
+
+              if (!found->second)
+                continue;
+              returnedSameValue = true;
+            }
+          }
       }
     }
 
@@ -9202,6 +9235,7 @@ bool GradientUtils::needsCacheWholeAllocation(
 
     // If caching this user, it cannot be a gep/cast of original
     if (!found->second) {
+      llvm::errs() << " mod: " << *oldFunc->getParent() << "\n";
       llvm::errs() << " oldFunc: " << *oldFunc << "\n";
       for (auto &pair : knownRecomputeHeuristic)
         llvm::errs() << " krc[" << *pair.first << "] = " << pair.second << "\n";
@@ -9211,8 +9245,9 @@ bool GradientUtils::needsCacheWholeAllocation(
     } else {
       // if not caching this user, it is legal to recompute, consider its users
       for (auto &use : cur->uses()) {
-        todo.push_back(std::make_pair(cast<Instruction>(use.getUser()),
-                                      use.getOperandNo()));
+        todo.push_back(std::make_tuple(cast<Instruction>(use.getUser()),
+                                       use.getOperandNo(),
+                                       returnedSameValue && orig));
       }
     }
   }

From c91e52400679a6604290f436d739d0aa4ef7d5ab Mon Sep 17 00:00:00 2001
From: "William S. Moses" <gh@wsmoses.com>
Date: Tue, 7 Nov 2023 23:59:15 -0500
Subject: [PATCH 4/4] Additional phi fix

---
 enzyme/Enzyme/FunctionUtils.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/enzyme/Enzyme/FunctionUtils.cpp b/enzyme/Enzyme/FunctionUtils.cpp
index 703e0d833a76..f4077d8e3fde 100644
--- a/enzyme/Enzyme/FunctionUtils.cpp
+++ b/enzyme/Enzyme/FunctionUtils.cpp
@@ -1047,6 +1047,7 @@ static void SimplifyMPIQueries(Function &NewF, FunctionAnalysisManager &FAM) {
     B.SetInsertPoint(res);
 
     if (auto PT = dyn_cast<PointerType>(storePointer->getType())) {
+      (void)PT;
 #if LLVM_VERSION_MAJOR < 17
 #if LLVM_VERSION_MAJOR >= 15
       if (PT->getContext().supportsTypedPointers()) {
@@ -4659,7 +4660,8 @@ std::optional<std::string> fixSparse_inner(Instruction *cur, llvm::Function &F,
             legal = false;
           auto L = LI.getLoopFor(PN->getParent());
           if (legal && L && L->getLoopPreheader() &&
-              L->getCanonicalInductionVariable()) {
+              L->getCanonicalInductionVariable() &&
+              L->getHeader() == PN->getParent()) {
             auto ph_idx = PN->getBasicBlockIndex(L->getLoopPreheader());
             if (isa<ConstantInt>(PN->getIncomingValue(ph_idx))) {
               lhsOps[ph_idx] =