[llvm] [LV] Add early-exit-with-store tests (PR #140899)

via llvm-commits llvm-commits at lists.llvm.org
Wed May 21 06:33:42 PDT 2025


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Graham Hunter (huntergr-arm)

<details>
<summary>Changes</summary>

Adds some additional LoopVectorizeLegality tests for early exit loops
with a store that we don't vectorize.

Test precommit split from #<!-- -->137774

---
Full diff: https://github.com/llvm/llvm-project/pull/140899.diff


1 Files Affected:

- (modified) llvm/test/Transforms/LoopVectorize/early_exit_legality.ll (+186) 


``````````diff
diff --git a/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll b/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
index de455c81d363e..b6a497fe4a672 100644
--- a/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
+++ b/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
@@ -470,6 +470,192 @@ loop.end:
   ret i64 %retval
 }
 
+define void @loop_contains_store_single_user(ptr dereferenceable(40) noalias %array, ptr align 2 dereferenceable(40) readonly %pred) {
+; CHECK-LABEL: LV: Checking a loop in 'loop_contains_store_single_user'
+; CHECK:       LV: Not vectorizing: Writes to memory unsupported in early exit loops.
+entry:
+  br label %for.body
+
+for.body:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %for.inc ]
+  %st.addr = getelementptr inbounds nuw i16, ptr %array, i64 %iv
+  %data = load i16, ptr %st.addr, align 2
+  %inc = add nsw i16 %data, 1
+  store i16 %inc, ptr %st.addr, align 2
+  %ee.addr = getelementptr inbounds nuw i16, ptr %pred, i64 %iv
+  %ee.val = load i16, ptr %ee.addr, align 2
+  %ee.cond = icmp sgt i16 %ee.val, 500
+  br i1 %ee.cond, label %exit, label %for.inc
+
+for.inc:
+  %iv.next = add nuw nsw i64 %iv, 1
+  %counted.cond = icmp eq i64 %iv.next, 20
+  br i1 %counted.cond, label %exit, label %for.body
+
+exit:
+  ret void
+}
+
+define void @loop_contains_store_multi_user(ptr dereferenceable(40) noalias %array, ptr align 2 dereferenceable(40) readonly %pred) {
+; CHECK-LABEL: LV: Checking a loop in 'loop_contains_store_multi_user'
+; CHECK:       LV: Not vectorizing: Writes to memory unsupported in early exit loops.
+entry:
+  br label %for.body
+
+for.body:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %for.inc ]
+  %st.addr = getelementptr inbounds nuw i16, ptr %array, i64 %iv
+  %data = load i16, ptr %st.addr, align 2
+  %inc = add nsw i16 %data, 1
+  store i16 %inc, ptr %st.addr, align 2
+  %ee.addr = getelementptr inbounds nuw i16, ptr %pred, i64 %iv
+  %ee.val = load i16, ptr %ee.addr, align 2
+  %ee.cond = icmp sgt i16 %ee.val, 500
+  %unused = add i16 %ee.val, 42
+  br i1 %ee.cond, label %exit, label %for.inc
+
+for.inc:
+  %iv.next = add nuw nsw i64 %iv, 1
+  %counted.cond = icmp eq i64 %iv.next, 20
+  br i1 %counted.cond, label %exit, label %for.body
+
+exit:
+  ret void
+}
+
+define void @loop_contains_store_fcmp(ptr dereferenceable(40) noalias %array, ptr align 2 dereferenceable(40) readonly %pred) {
+; CHECK-LABEL: LV: Checking a loop in 'loop_contains_store_fcmp'
+; CHECK:       LV: Not vectorizing: Writes to memory unsupported in early exit loops.
+entry:
+  br label %for.body
+
+for.body:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %for.inc ]
+  %st.addr = getelementptr inbounds nuw i16, ptr %array, i64 %iv
+  %data = load i16, ptr %st.addr, align 2
+  %inc = add nsw i16 %data, 1
+  store i16 %inc, ptr %st.addr, align 2
+  %ee.addr = getelementptr inbounds nuw half, ptr %pred, i64 %iv
+  %ee.val = load half, ptr %ee.addr, align 2
+  %ee.cond = fcmp ugt half %ee.val, 500.0
+  br i1 %ee.cond, label %exit, label %for.inc
+
+for.inc:
+  %iv.next = add nuw nsw i64 %iv, 1
+  %counted.cond = icmp eq i64 %iv.next, 20
+  br i1 %counted.cond, label %exit, label %for.body
+
+exit:
+  ret void
+}
+
+define void @loop_contains_store_safe_dependency(ptr dereferenceable(40) noalias %array, ptr align 2 dereferenceable(80) readonly %pred) {
+; CHECK-LABEL: LV: Checking a loop in 'loop_contains_store_safe_dependency'
+; CHECK:       LV: Not vectorizing: Writes to memory unsupported in early exit loops.
+entry:
+  %forward = getelementptr i16, ptr %pred, i64 -8
+  br label %for.body
+
+for.body:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %for.inc ]
+  %st.addr = getelementptr inbounds nuw i16, ptr %array, i64 %iv
+  %data = load i16, ptr %st.addr, align 2
+  %inc = add nsw i16 %data, 1
+  store i16 %inc, ptr %st.addr, align 2
+  %ee.addr = getelementptr inbounds nuw i16, ptr %pred, i64 %iv
+  %ee.val = load i16, ptr %ee.addr, align 2
+  %ee.cond = icmp sgt i16 %ee.val, 500
+  %some.addr = getelementptr inbounds nuw i16, ptr %forward, i64 %iv
+  store i16 42, ptr %some.addr, align 2
+  br i1 %ee.cond, label %exit, label %for.inc
+
+for.inc:
+  %iv.next = add nuw nsw i64 %iv, 1
+  %counted.cond = icmp eq i64 %iv.next, 20
+  br i1 %counted.cond, label %exit, label %for.body
+
+exit:
+  ret void
+}
+
+define void @loop_contains_store_assumed_bounds(ptr noalias %array, ptr readonly %pred, i32 %n) {
+; CHECK-LABEL: LV: Checking a loop in 'loop_contains_store_assumed_bounds'
+; CHECK:       LV: Not vectorizing: Writes to memory unsupported in early exit loops.
+entry:
+  %n_bytes = mul nuw nsw i32 %n, 2
+  call void @llvm.assume(i1 true) [ "align"(ptr %pred, i64 2), "dereferenceable"(ptr %pred, i32 %n_bytes) ]
+  %tc = sext i32 %n to i64
+  br label %for.body
+
+for.body:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %for.inc ]
+  %st.addr = getelementptr inbounds nuw i16, ptr %array, i64 %iv
+  %data = load i16, ptr %st.addr, align 2
+  %inc = add nsw i16 %data, 1
+  store i16 %inc, ptr %st.addr, align 2
+  %ee.addr = getelementptr inbounds nuw i16, ptr %pred, i64 %iv
+  %ee.val = load i16, ptr %ee.addr, align 2
+  %ee.cond = icmp sgt i16 %ee.val, 500
+  br i1 %ee.cond, label %exit, label %for.inc
+
+for.inc:
+  %iv.next = add nuw nsw i64 %iv, 1
+  %counted.cond = icmp eq i64 %iv.next, %tc
+  br i1 %counted.cond, label %exit, label %for.body
+
+exit:
+  ret void
+}
+
+define void @loop_contains_store_volatile(ptr dereferenceable(40) noalias %array, ptr align 2 dereferenceable(40) readonly %pred) {
+; CHECK-LABEL: LV: Checking a loop in 'loop_contains_store_volatile'
+; CHECK:       LV: Not vectorizing: Writes to memory unsupported in early exit loops.
+entry:
+  br label %for.body
+
+for.body:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %for.inc ]
+  %st.addr = getelementptr inbounds nuw i16, ptr %array, i64 %iv
+  %data = load i16, ptr %st.addr, align 2
+  %inc = add nsw i16 %data, 1
+  store volatile i16 %inc, ptr %st.addr, align 2
+  %ee.addr = getelementptr inbounds nuw i16, ptr %pred, i64 %iv
+  %ee.val = load i16, ptr %ee.addr, align 2
+  %ee.cond = icmp sgt i16 %ee.val, 500
+  br i1 %ee.cond, label %exit, label %for.inc
+
+for.inc:
+  %iv.next = add nuw nsw i64 %iv, 1
+  %counted.cond = icmp eq i64 %iv.next, 20
+  br i1 %counted.cond, label %exit, label %for.body
+
+exit:
+  ret void
+}
+
+define void @exit_conditions_combined(ptr noalias dereferenceable(40) %array, ptr readonly align 2 dereferenceable(40) %pred) {
+; CHECK-LABEL: LV: Checking a loop in 'exit_conditions_combined'
+; CHECK:       LV: Not vectorizing: Cannot vectorize uncountable loop.
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %for.body ]
+  %st.addr = getelementptr inbounds nuw i16, ptr %array, i64 %iv
+  %data = load i16, ptr %st.addr, align 2
+  %inc = add nsw i16 %data, 1
+  store i16 %inc, ptr %st.addr, align 2
+  %ee.addr = getelementptr inbounds nuw i16, ptr %pred, i64 %iv
+  %ee.val = load i16, ptr %ee.addr, align 2
+  %ee.cond = icmp sgt i16 %ee.val, 500
+  %iv.next = add nuw nsw i64 %iv, 1
+  %counted.cond = icmp eq i64 %iv.next, 20
+  %or.cond = select i1 %ee.cond, i1 true, i1 %counted.cond
+  br i1 %or.cond, label %exit, label %for.body
+
+exit:                                             ; preds = %for.body
+  ret void
+}
 
 define i64 @uncountable_exit_in_conditional_block(ptr %mask) {
 ; CHECK-LABEL: LV: Checking a loop in 'uncountable_exit_in_conditional_block'

``````````

</details>


https://github.com/llvm/llvm-project/pull/140899


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