[llvm-branch-commits] [llvm] release/18.x: [ArgPromotion] Remove incorrect TranspBlocks set for loads. (#84835) (PR #84945)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: None (llvmbot)

<details>
<summary>Changes</summary>

Backport 31ffdb56b4df9b772d763dccabbfde542545d695 bba4a1daff6ee09941f1369a4e56b4af95efdc5c

Requested by: @<!-- -->nikic

---
Full diff: https://github.com/llvm/llvm-project/pull/84945.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/IPO/ArgumentPromotion.cpp (+1-5) 
- (added) llvm/test/Transforms/ArgumentPromotion/aliasing-and-non-aliasing-loads-with-clobber.ll (+100) 


``````````diff
diff --git a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
index 8058282c422503..062a3d341007ce 100644
--- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -652,10 +652,6 @@ static bool findArgParts(Argument *Arg, const DataLayout &DL, AAResults &AAR,
   // check to see if the pointer is guaranteed to not be modified from entry of
   // the function to each of the load instructions.
 
-  // Because there could be several/many load instructions, remember which
-  // blocks we know to be transparent to the load.
-  df_iterator_default_set<BasicBlock *, 16> TranspBlocks;
-
   for (LoadInst *Load : Loads) {
     // Check to see if the load is invalidated from the start of the block to
     // the load itself.
@@ -669,7 +665,7 @@ static bool findArgParts(Argument *Arg, const DataLayout &DL, AAResults &AAR,
     // To do this, we perform a depth first search on the inverse CFG from the
     // loading block.
     for (BasicBlock *P : predecessors(BB)) {
-      for (BasicBlock *TranspBB : inverse_depth_first_ext(P, TranspBlocks))
+      for (BasicBlock *TranspBB : inverse_depth_first(P))
         if (AAR.canBasicBlockModify(*TranspBB, Loc))
           return false;
     }
diff --git a/llvm/test/Transforms/ArgumentPromotion/aliasing-and-non-aliasing-loads-with-clobber.ll b/llvm/test/Transforms/ArgumentPromotion/aliasing-and-non-aliasing-loads-with-clobber.ll
new file mode 100644
index 00000000000000..1e1669b29b0db6
--- /dev/null
+++ b/llvm/test/Transforms/ArgumentPromotion/aliasing-and-non-aliasing-loads-with-clobber.ll
@@ -0,0 +1,100 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -p argpromotion -S %s | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+
+ at f = dso_local global { i16, i64 } { i16 1, i64 0 }, align 8
+
+; Test case for https://github.com/llvm/llvm-project/issues/84807.
+
+; Make sure the loads from @callee are not moved to @caller, as the store
+; in %then may aliases to load from %q.
+
+define i32 @caller1(i1 %c) {
+; CHECK-LABEL: define i32 @caller1(
+; CHECK-SAME: i1 [[C:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    call void @callee1(ptr noundef nonnull @f, i1 [[C]])
+; CHECK-NEXT:    ret i32 0
+;
+entry:
+  call void @callee1(ptr noundef nonnull @f, i1 %c)
+  ret i32 0
+}
+
+define internal void @callee1(ptr nocapture noundef readonly %q, i1 %c) {
+; CHECK-LABEL: define internal void @callee1(
+; CHECK-SAME: ptr nocapture noundef readonly [[Q:%.*]], i1 [[C:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C]], label [[THEN:%.*]], label [[EXIT:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    store i16 123, ptr @f, align 8
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[Q_0_VAL:%.*]] = load i16, ptr [[Q]], align 8
+; CHECK-NEXT:    [[GEP_8:%.*]] = getelementptr inbounds i8, ptr [[Q]], i64 8
+; CHECK-NEXT:    [[Q_8_VAL:%.*]] = load i64, ptr [[GEP_8]], align 8
+; CHECK-NEXT:    call void @use(i16 [[Q_0_VAL]], i64 [[Q_8_VAL]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  br i1 %c, label %then, label %exit
+
+then:
+  store i16 123, ptr @f, align 8
+  br label %exit
+
+exit:
+  %l.0 = load i16, ptr %q, align 8
+  %gep.8  = getelementptr inbounds i8, ptr %q, i64 8
+  %l.1 = load i64, ptr %gep.8, align 8
+  call void @use(i16 %l.0, i64 %l.1)
+  ret void
+
+  uselistorder ptr %q, { 1, 0 }
+}
+
+; Same as @caller1/callee2, but with default uselist order.
+define i32 @caller2(i1 %c) {
+; CHECK-LABEL: define i32 @caller2(
+; CHECK-SAME: i1 [[C:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    call void @callee2(ptr noundef nonnull @f, i1 [[C]])
+; CHECK-NEXT:    ret i32 0
+;
+entry:
+  call void @callee2(ptr noundef nonnull @f, i1 %c)
+  ret i32 0
+}
+
+define internal void @callee2(ptr nocapture noundef readonly %q, i1 %c) {
+; CHECK-LABEL: define internal void @callee2(
+; CHECK-SAME: ptr nocapture noundef readonly [[Q:%.*]], i1 [[C:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C]], label [[THEN:%.*]], label [[EXIT:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    store i16 123, ptr @f, align 8
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[Q_0_VAL:%.*]] = load i16, ptr [[Q]], align 8
+; CHECK-NEXT:    [[GEP_8:%.*]] = getelementptr inbounds i8, ptr [[Q]], i64 8
+; CHECK-NEXT:    [[Q_8_VAL:%.*]] = load i64, ptr [[GEP_8]], align 8
+; CHECK-NEXT:    call void @use(i16 [[Q_0_VAL]], i64 [[Q_8_VAL]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  br i1 %c, label %then, label %exit
+
+then:
+  store i16 123, ptr @f, align 8
+  br label %exit
+
+exit:
+  %l.0 = load i16, ptr %q, align 8
+  %gep.8  = getelementptr inbounds i8, ptr %q, i64 8
+  %l.1 = load i64, ptr %gep.8, align 8
+  call void @use(i16 %l.0, i64 %l.1)
+  ret void
+}
+
+declare void @use(i16, i64)

``````````

</details>


https://github.com/llvm/llvm-project/pull/84945