1 files changed, 66 insertions, 0 deletions
diff --git a/dev-lang/rust/files/1.61.0-llvm_selectInterleaveCount.patch b/dev-lang/rust/files/1.61.0-llvm_selectInterleaveCount.patch
new file mode 100644
index 000000000000..71a4e8df75d8
--- /dev/null
+++ b/dev-lang/rust/files/1.61.0-llvm_selectInterleaveCount.patch
@@ -0,0 +1,66 @@
+From fe8a27acd716a42667f5a572f52f2b04636010ff Mon Sep 17 00:00:00 2001
+From: Florian Hahn <flo@fhahn.com>
+Date: Tue, 29 Mar 2022 22:52:42 +0100
+Subject: [PATCH] [LV] Handle zero cost loops in selectInterleaveCount.
+
+In some case, like in the added test case, we can reach
+selectInterleaveCount with loops that actually have a cost of 0.
+
+Unfortunately a loop cost of 0 is also used to communicate that the cost
+has not been computed yet. To resolve the crash, bail out if the cost
+remains zero after computing it.
+
+This seems like the best option, as there are multiple code paths that
+return a cost of 0 to force a computation in selectInterleaveCount.
+Computing the cost at multiple places up front there would unnecessarily
+complicate the logic.
+
+Fixes #54413.
+
+(cherry picked from commit ecb4171dcbf1b433c9963fd605a74898303e850d)
+---
+ .../Transforms/Vectorize/LoopVectorize.cpp    | 22 ++++----
+ ...ct-interleave-count-loop-with-cost-zero.ll | 50 +++++++++++++++++++
+ 2 files changed, 62 insertions(+), 10 deletions(-)
+ create mode 100644 llvm/test/Transforms/LoopVectorize/X86/pr54413-select-interleave-count-loop-with-cost-zero.ll
+
+diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+index 21c16f07e237..e1cc7946073e 100644
+--- a/src/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
++++ b/src/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+@@ -6035,6 +6035,18 @@ unsigned LoopVectorizationCostModel::selectInterleaveCount(ElementCount VF,
+       !(InterleaveSmallLoopScalarReduction && HasReductions && VF.isScalar()))
+     return 1;
+ 
++  // If we did not calculate the cost for VF (because the user selected the VF)
++  // then we calculate the cost of VF here.
++  if (LoopCost == 0) {
++    InstructionCost C = expectedCost(VF).first;
++    assert(C.isValid() && "Expected to have chosen a VF with valid cost");
++    LoopCost = *C.getValue();
++
++    // Loop body is free and there is no need for interleaving.
++    if (LoopCost == 0)
++      return 1;
++  }
++
+   RegisterUsage R = calculateRegisterUsage({VF})[0];
+   // We divide by these constants so assume that we have at least one
+   // instruction that uses at least one register.
+@@ -6126,16 +6138,6 @@ unsigned LoopVectorizationCostModel::selectInterleaveCount(ElementCount VF,
+ 
+   assert(IC > 0 && "Interleave count must be greater than 0.");
+ 
+-  // If we did not calculate the cost for VF (because the user selected the VF)
+-  // then we calculate the cost of VF here.
+-  if (LoopCost == 0) {
+-    InstructionCost C = expectedCost(VF).first;
+-    assert(C.isValid() && "Expected to have chosen a VF with valid cost");
+-    LoopCost = *C.getValue();
+-  }
+-
+-  assert(LoopCost && "Non-zero loop cost expected");
+-
+   // Interleave if we vectorized this loop and there is a reduction that could
+   // benefit from interleaving.
+   if (VF.isVector() && HasReductions) {