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The experimental_cttz_elts intrinsic currently returns a cost
of 1 for all types, however we know that it currently requires
2 SVE instructions when lowering this - brkb and cntp. Both of
these instructions have a throughput that is half of a basic
vector instruction such as a vector add. This patch bumps the
cost of this intrinsic up to 4 to reflect two instructions of
lower throughput.

The experimental_cttz_elts intrinsic currently returns a cost
of 1 for all types, however we know that it currently requires
2 SVE instructions when lowering this - brkb and cntp. Both
of these instructions have a throughput that is half of a
basic vector instruction such as a vector add. This patch bumps
the cost of this intrinsic up to 4 to reflect two instructions
of lower throughput.
@llvmbot llvmbot added backend:AArch64 llvm:analysis Includes value tracking, cost tables and constant folding labels Jan 30, 2025
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llvmbot commented Jan 30, 2025

@llvm/pr-subscribers-llvm-analysis

@llvm/pr-subscribers-backend-aarch64

Author: David Sherwood (david-arm)

Changes

The experimental_cttz_elts intrinsic currently returns a cost
of 1 for all types, however we know that it currently requires
2 SVE instructions when lowering this - brkb and cntp. Both of
these instructions have a throughput that is half of a basic
vector instruction such as a vector add. This patch bumps the
cost of this intrinsic up to 4 to reflect two instructions of
lower throughput.


Patch is 26.92 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/125093.diff

2 Files Affected:

  • (modified) llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp (+10)
  • (modified) llvm/test/Analysis/CostModel/AArch64/cttz_elts.ll (+64-64)
diff --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index aae2fdaf5bec37..a6edcf125782b2 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -940,6 +940,16 @@ AArch64TTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
     }
     break;
   }
+  case Intrinsic::experimental_cttz_elts: {
+    EVT ArgVT = getTLI()->getValueType(DL, ICA.getArgTypes()[0]);
+    if (!getTLI()->shouldExpandCttzElements(ArgVT)) {
+      // This will consist of a SVE brkb and a cntp instruction. These
+      // typically have the same latency and half the throughput as a vector
+      // add instruction.
+      return 4;
+    }
+    break;
+  }
   default:
     break;
   }
diff --git a/llvm/test/Analysis/CostModel/AArch64/cttz_elts.ll b/llvm/test/Analysis/CostModel/AArch64/cttz_elts.ll
index 98d5bd5bd13f43..5a2d08a17fca47 100644
--- a/llvm/test/Analysis/CostModel/AArch64/cttz_elts.ll
+++ b/llvm/test/Analysis/CostModel/AArch64/cttz_elts.ll
@@ -4,45 +4,45 @@
 define void @foo_no_vscale_range() {
 ; CHECK-LABEL: 'foo_no_vscale_range'
 ; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %res.i64.nxv1i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv1i1(<vscale x 1 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv2i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv2i1(<vscale x 2 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv4i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv8i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv8i1(<vscale x 8 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv16i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv2i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv2i1(<vscale x 2 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv4i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv8i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv8i1(<vscale x 8 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv16i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> undef, i1 true)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 96 for instruction: %res.i64.nxv32i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv32i1(<vscale x 32 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv2i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv2i1(<vscale x 2 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv4i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv4i1(<vscale x 4 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv8i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv8i1(<vscale x 8 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv16i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv16i1(<vscale x 16 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv2i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv2i1(<vscale x 2 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv4i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv4i1(<vscale x 4 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv8i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv8i1(<vscale x 8 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv16i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv16i1(<vscale x 16 x i1> undef, i1 true)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 48 for instruction: %res.i32.nxv32i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv32i1(<vscale x 32 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.v2i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v2i1(<2 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.v4i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v4i1(<4 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.v8i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v8i1(<8 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.v16i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v16i1(<16 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.v2i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v2i1(<2 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.v4i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v4i1(<4 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.v8i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v8i1(<8 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.v16i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v16i1(<16 x i1> undef, i1 true)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 12 for instruction: %res.i64.v32i1.zip = call i64 @llvm.experimental.cttz.elts.i64.v32i1(<32 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.v2i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v2i1(<2 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.v4i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v4i1(<4 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.v8i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v8i1(<8 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.v16i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v16i1(<16 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.v2i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v2i1(<2 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.v4i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v4i1(<4 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.v8i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v8i1(<8 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.v16i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v16i1(<16 x i1> undef, i1 true)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 12 for instruction: %res.i32.v32i1.zip = call i32 @llvm.experimental.cttz.elts.i32.v32i1(<32 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv2i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv2i1(<vscale x 2 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv4i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv8i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv8i1(<vscale x 8 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv16i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv2i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv2i1(<vscale x 2 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv4i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv8i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv8i1(<vscale x 8 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv16i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> undef, i1 false)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 96 for instruction: %res.i64.nxv32i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv32i1(<vscale x 32 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv2i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv2i1(<vscale x 2 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv4i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv4i1(<vscale x 4 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv8i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv8i1(<vscale x 8 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv16i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv16i1(<vscale x 16 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv2i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv2i1(<vscale x 2 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv4i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv4i1(<vscale x 4 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv8i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv8i1(<vscale x 8 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv16i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv16i1(<vscale x 16 x i1> undef, i1 false)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 48 for instruction: %res.i32.nxv32i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv32i1(<vscale x 32 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.v2i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v2i1(<2 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.v4i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v4i1(<4 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.v8i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v8i1(<8 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.v16i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v16i1(<16 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.v2i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v2i1(<2 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.v4i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v4i1(<4 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.v8i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v8i1(<8 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.v16i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v16i1(<16 x i1> undef, i1 false)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 12 for instruction: %res.i64.v32i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.v32i1(<32 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.v2i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v2i1(<2 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.v4i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v4i1(<4 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.v8i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v8i1(<8 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.v16i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v16i1(<16 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.v2i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v2i1(<2 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.v4i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v4i1(<4 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.v8i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v8i1(<8 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.v16i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v16i1(<16 x i1> undef, i1 false)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 12 for instruction: %res.i32.v32i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.v32i1(<32 x i1> undef, i1 false)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret void
 ;
@@ -97,25 +97,25 @@ define void @foo_no_vscale_range() {
 
 define void @foo_vscale_range_1_16() vscale_range(1,16) {
 ; CHECK-LABEL: 'foo_vscale_range_1_16'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv2i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv2i1(<vscale x 2 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv4i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv8i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv8i1(<vscale x 8 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv16i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv2i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv2i1(<vscale x 2 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv4i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv8i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv8i1(<vscale x 8 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv16i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> undef, i1 true)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 24 for instruction: %res.i64.nxv32i1.zip = call i64 @llvm.experimental.cttz.elts.i64.nxv32i1(<vscale x 32 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv2i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv2i1(<vscale x 2 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv4i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv4i1(<vscale x 4 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv8i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv8i1(<vscale x 8 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv16i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv16i1(<vscale x 16 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv2i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv2i1(<vscale x 2 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv4i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv4i1(<vscale x 4 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv8i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv8i1(<vscale x 8 x i1> undef, i1 true)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv16i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv16i1(<vscale x 16 x i1> undef, i1 true)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 24 for instruction: %res.i32.nxv32i1.zip = call i32 @llvm.experimental.cttz.elts.i32.nxv32i1(<vscale x 32 x i1> undef, i1 true)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv2i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv2i1(<vscale x 2 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv4i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv8i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv8i1(<vscale x 8 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i64.nxv16i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv2i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv2i1(<vscale x 2 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv4i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv8i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv8i1(<vscale x 8 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i64.nxv16i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> undef, i1 false)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 24 for instruction: %res.i64.nxv32i1.nzip = call i64 @llvm.experimental.cttz.elts.i64.nxv32i1(<vscale x 32 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv2i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv2i1(<vscale x 2 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv4i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv4i1(<vscale x 4 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv8i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv8i1(<vscale x 8 x i1> undef, i1 false)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %res.i32.nxv16i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv16i1(<vscale x 16 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv2i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv2i1(<vscale x 2 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv4i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv4i1(<vscale x 4 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv8i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv8i1(<vscale x 8 x i1> undef, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %res.i32.nxv16i1.nzip = call i32 @llvm.experimental.cttz.elts.i32.nxv16i1(<vscale x 16 ...
[truncated]

@david-arm david-arm merged commit de5d588 into llvm:main Feb 4, 2025
9 of 11 checks passed
Icohedron pushed a commit to Icohedron/llvm-project that referenced this pull request Feb 11, 2025
…25093)

The experimental_cttz_elts intrinsic currently returns a cost
of 1 for all types, however we know that it currently requires
2 SVE instructions when lowering this - brkb and cntp. Both of
these instructions have a throughput that is half of a basic
vector instruction such as a vector add. This patch bumps the
cost of this intrinsic up to 4 to reflect two instructions of
lower throughput.
@david-arm david-arm deleted the cttz_elts_cost branch April 7, 2025 16:08
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