[llvm] [SCEV] Add range attribute handling. (PR #88449)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: Andreas Jonson (andjo403)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/88449.diff


2 Files Affected:

- (modified) llvm/lib/Analysis/ScalarEvolution.cpp (+8-1) 
- (added) llvm/test/Analysis/ScalarEvolution/range-attribute.ll (+74) 


``````````diff
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 9fcce797f55976..95440dda3b4c0e 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -6382,9 +6382,16 @@ uint32_t ScalarEvolution::getMinTrailingZeros(const SCEV *S) {
 
 /// Helper method to assign a range to V from metadata present in the IR.
 static std::optional<ConstantRange> GetRangeFromMetadata(Value *V) {
-  if (Instruction *I = dyn_cast<Instruction>(V))
+  if (Instruction *I = dyn_cast<Instruction>(V)) {
     if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
       return getConstantRangeFromMetadata(*MD);
+    if (const auto *CB = dyn_cast<CallBase>(V))
+      if (std::optional<ConstantRange> Range = CB->getRange())
+        return Range;
+  }
+  if (auto *A = dyn_cast<Argument>(V))
+    if (std::optional<ConstantRange> Range = A->getRange())
+      return Range;
 
   return std::nullopt;
 }
diff --git a/llvm/test/Analysis/ScalarEvolution/range-attribute.ll b/llvm/test/Analysis/ScalarEvolution/range-attribute.ll
new file mode 100644
index 00000000000000..ea22695e58d1da
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/range-attribute.ll
@@ -0,0 +1,74 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -disable-output "-passes=print<scalar-evolution>" -scalar-evolution-classify-expressions=0 < %s 2>&1 | FileCheck %s
+
+define i32 @slt_trip_count_with_range_attr(i32 range(i32 1, 100) %limit) {
+;
+; CHECK-LABEL: 'slt_trip_count_with_range_attr'
+; CHECK-NEXT:  Determining loop execution counts for: @slt_trip_count_with_range_attr
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (-1 + %limit)<nsw>
+; CHECK-NEXT:  Loop %loop: constant max backedge-taken count is i32 98
+; CHECK-NEXT:  Loop %loop: symbolic max backedge-taken count is (-1 + %limit)<nsw>
+; CHECK-NEXT:  Loop %loop: Trip multiple is 1
+;
+ entry:
+  br label %loop
+
+ loop:
+  %index = phi i32 [ 0, %entry ], [ %index.inc, %loop ]
+  %index.inc = add i32 %index, 1
+  %continue = icmp slt i32 %index.inc, %limit
+  br i1 %continue, label %loop, label %loop.exit
+
+ loop.exit:
+  ret i32 0
+}
+
+declare i32 @get_i32()
+
+define i32 @slt_trip_count_with_range_call() {
+;
+; CHECK-LABEL: 'slt_trip_count_with_range_call'
+; CHECK-NEXT:  Determining loop execution counts for: @slt_trip_count_with_range_call
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (-1 + %limit)<nsw>
+; CHECK-NEXT:  Loop %loop: constant max backedge-taken count is i32 98
+; CHECK-NEXT:  Loop %loop: symbolic max backedge-taken count is (-1 + %limit)<nsw>
+; CHECK-NEXT:  Loop %loop: Trip multiple is 1
+;
+ entry:
+  %limit = call range(i32 1, 100) i32 @get_i32()
+  br label %loop
+
+ loop:
+  %index = phi i32 [ 0, %entry ], [ %index.inc, %loop ]
+  %index.inc = add i32 %index, 1
+  %continue = icmp slt i32 %index.inc, %limit
+  br i1 %continue, label %loop, label %loop.exit
+
+ loop.exit:
+  ret i32 0
+}
+
+declare range(i32 1, 100) i32 @get_i32_in_range()
+
+define i32 @slt_trip_count_with_range_result() {
+;
+; CHECK-LABEL: 'slt_trip_count_with_range_result'
+; CHECK-NEXT:  Determining loop execution counts for: @slt_trip_count_with_range_result
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (-1 + %limit)<nsw>
+; CHECK-NEXT:  Loop %loop: constant max backedge-taken count is i32 98
+; CHECK-NEXT:  Loop %loop: symbolic max backedge-taken count is (-1 + %limit)<nsw>
+; CHECK-NEXT:  Loop %loop: Trip multiple is 1
+;
+ entry:
+  %limit = call i32 @get_i32_in_range()
+  br label %loop
+
+ loop:
+  %index = phi i32 [ 0, %entry ], [ %index.inc, %loop ]
+  %index.inc = add i32 %index, 1
+  %continue = icmp slt i32 %index.inc, %limit
+  br i1 %continue, label %loop, label %loop.exit
+
+ loop.exit:
+  ret i32 0
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/88449