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-rw-r--r--llvm/lib/Transforms/Scalar/NewGVN.cpp9
-rw-r--r--llvm/test/Transforms/NewGVN/phi-of-ops-loads.ll70
-rw-r--r--llvm/test/Transforms/NewGVN/storeoverstore.ll33
3 files changed, 85 insertions, 27 deletions
diff --git a/llvm/lib/Transforms/Scalar/NewGVN.cpp b/llvm/lib/Transforms/Scalar/NewGVN.cpp
index 6890ad38..2476e6c4 100644
--- a/llvm/lib/Transforms/Scalar/NewGVN.cpp
+++ b/llvm/lib/Transforms/Scalar/NewGVN.cpp
@@ -2587,6 +2587,15 @@ bool NewGVN::OpIsSafeForPHIOfOpsHelper(
}
auto *OrigI = cast<Instruction>(V);
+ // When we hit an instruction that reads memory (load, call, etc), we must
+ // consider any store that may happen in the loop. For now, we assume the
+ // worst: there is a store in the loop that alias with this read.
+ // The case where the load is outside the loop is already covered by the
+ // dominator check above.
+ // TODO: relax this condition
+ if (OrigI->mayReadFromMemory())
+ return false;
+
for (auto *Op : OrigI->operand_values()) {
if (!isa<Instruction>(Op))
continue;
diff --git a/llvm/test/Transforms/NewGVN/phi-of-ops-loads.ll b/llvm/test/Transforms/NewGVN/phi-of-ops-loads.ll
index 63a16d6..335b3b0 100644
--- a/llvm/test/Transforms/NewGVN/phi-of-ops-loads.ll
+++ b/llvm/test/Transforms/NewGVN/phi-of-ops-loads.ll
@@ -1,15 +1,15 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -passes=newgvn -enable-phi-of-ops=true -S -o - %s | FileCheck %s
-define void @store-in-loop(i8* %p, i8* %q) {
-; CHECK-LABEL: @store-in-loop(
+define void @hoisted-load(i8* %p, i8* %q) {
+; CHECK-LABEL: @hoisted-load(
; CHECK-NEXT: bb56:
+; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
; CHECK-NEXT: br label [[BB57:%.*]]
; CHECK: bb57:
; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
; CHECK-NEXT: [[IDX:%.*]] = phi i8 [ 0, [[BB56]] ], [ [[INC:%.*]], [[BB229]] ]
-; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
; CHECK: bb229:
@@ -20,6 +20,44 @@ define void @store-in-loop(i8* %p, i8* %q) {
; CHECK-NEXT: ret void
;
bb56:
+ %n60 = load i8, i8* %p
+ br label %bb57
+
+bb57:
+ %n59 = phi i1 [ false, %bb229 ], [ true, %bb56 ]
+ %idx = phi i8 [0, %bb56], [%inc, %bb229]
+ %n62 = icmp ne i8 %n60, 2
+ %n63 = or i1 %n59, %n62
+ br i1 %n63, label %bb229, label %bb237
+
+bb229:
+ %inc = add i8 %idx, 1
+ store i8 %inc, i8* %q
+ br label %bb57
+
+bb237:
+ ret void
+}
+
+define void @store-in-loop(i8* %p, i8* %q) {
+; CHECK-LABEL: @store-in-loop(
+; CHECK-NEXT: bb56:
+; CHECK-NEXT: br label [[BB57:%.*]]
+; CHECK: bb57:
+; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229:%.*]] ], [ true, [[BB56:%.*]] ]
+; CHECK-NEXT: [[IDX:%.*]] = phi i8 [ 0, [[BB56]] ], [ [[INC:%.*]], [[BB229]] ]
+; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
+; CHECK-NEXT: [[N62:%.*]] = icmp ne i8 [[N60]], 2
+; CHECK-NEXT: [[N63:%.*]] = or i1 [[N59]], [[N62]]
+; CHECK-NEXT: br i1 [[N63]], label [[BB229]], label [[BB237:%.*]]
+; CHECK: bb229:
+; CHECK-NEXT: [[INC]] = add i8 [[IDX]], 1
+; CHECK-NEXT: store i8 [[INC]], i8* [[Q:%.*]], align 1
+; CHECK-NEXT: br label [[BB57]]
+; CHECK: bb237:
+; CHECK-NEXT: ret void
+;
+bb56:
br label %bb57
bb57:
@@ -39,17 +77,18 @@ bb237:
ret void
}
+; TODO: we should support this case
define void @no-alias-store-in-loop(i8* noalias %p, i8* noalias %q) {
; CHECK-LABEL: @no-alias-store-in-loop(
; CHECK-NEXT: bb56:
; CHECK-NEXT: br label [[BB57:%.*]]
; CHECK: bb57:
-; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
-; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
+; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229:%.*]] ], [ true, [[BB56:%.*]] ]
; CHECK-NEXT: [[IDX:%.*]] = phi i8 [ 0, [[BB56]] ], [ [[INC:%.*]], [[BB229]] ]
; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
-; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
-; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
+; CHECK-NEXT: [[N62:%.*]] = icmp ne i8 [[N60]], 2
+; CHECK-NEXT: [[N63:%.*]] = or i1 [[N59]], [[N62]]
+; CHECK-NEXT: br i1 [[N63]], label [[BB229]], label [[BB237:%.*]]
; CHECK: bb229:
; CHECK-NEXT: [[INC]] = add i8 [[IDX]], 1
; CHECK-NEXT: store i8 [[INC]], i8* [[Q:%.*]], align 1
@@ -82,11 +121,11 @@ define void @function-in-loop(i8* %p) {
; CHECK-NEXT: bb56:
; CHECK-NEXT: br label [[BB57:%.*]]
; CHECK: bb57:
-; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
-; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
+; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229:%.*]] ], [ true, [[BB56:%.*]] ]
; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
-; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
-; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
+; CHECK-NEXT: [[N62:%.*]] = icmp ne i8 [[N60]], 2
+; CHECK-NEXT: [[N63:%.*]] = or i1 [[N59]], [[N62]]
+; CHECK-NEXT: br i1 [[N63]], label [[BB229]], label [[BB237:%.*]]
; CHECK: bb229:
; CHECK-NEXT: call void @f()
; CHECK-NEXT: br label [[BB57]]
@@ -111,16 +150,17 @@ bb237:
ret void
}
+; TODO: we should support this case
define void @nowrite-function-in-loop(i8* %p) {
; CHECK-LABEL: @nowrite-function-in-loop(
; CHECK-NEXT: bb56:
; CHECK-NEXT: br label [[BB57:%.*]]
; CHECK: bb57:
-; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
-; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
+; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229:%.*]] ], [ true, [[BB56:%.*]] ]
; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
-; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
-; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
+; CHECK-NEXT: [[N62:%.*]] = icmp ne i8 [[N60]], 2
+; CHECK-NEXT: [[N63:%.*]] = or i1 [[N59]], [[N62]]
+; CHECK-NEXT: br i1 [[N63]], label [[BB229]], label [[BB237:%.*]]
; CHECK: bb229:
; CHECK-NEXT: call void @f() #[[ATTR0:[0-9]+]]
; CHECK-NEXT: br label [[BB57]]
diff --git a/llvm/test/Transforms/NewGVN/storeoverstore.ll b/llvm/test/Transforms/NewGVN/storeoverstore.ll
index 385f187..0e4a4ec 100644
--- a/llvm/test/Transforms/NewGVN/storeoverstore.ll
+++ b/llvm/test/Transforms/NewGVN/storeoverstore.ll
@@ -12,12 +12,16 @@ define i32 @foo(i32*, i32) {
; CHECK-NEXT: store i32 5, i32* [[TMP0:%.*]], align 4
; CHECK-NEXT: [[TMP3:%.*]] = icmp ne i32 [[TMP1:%.*]], 0
; CHECK-NEXT: br i1 [[TMP3]], label [[TMP4:%.*]], label [[TMP5:%.*]]
-; CHECK: br label [[TMP5]]
-; CHECK: [[PHIOFOPS:%.*]] = phi i32 [ 10, [[TMP2:%.*]] ], [ 15, [[TMP4]] ]
-; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ 10, [[TMP4]] ], [ 5, [[TMP2]] ]
-; CHECK-NEXT: br i1 [[TMP3]], label [[TMP6:%.*]], label [[TMP7:%.*]]
-; CHECK: br label [[TMP7]]
-; CHECK: [[DOT1:%.*]] = phi i32 [ [[PHIOFOPS]], [[TMP6]] ], [ [[DOT0]], [[TMP5]] ]
+; CHECK: 4:
+; CHECK-NEXT: br label [[TMP5]]
+; CHECK: 5:
+; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ 10, [[TMP4]] ], [ 5, [[TMP2:%.*]] ]
+; CHECK-NEXT: br i1 [[TMP3]], label [[TMP6:%.*]], label [[TMP8:%.*]]
+; CHECK: 6:
+; CHECK-NEXT: [[TMP7:%.*]] = add nsw i32 [[DOT0]], 5
+; CHECK-NEXT: br label [[TMP8]]
+; CHECK: 8:
+; CHECK-NEXT: [[DOT1:%.*]] = phi i32 [ [[TMP7]], [[TMP6]] ], [ [[DOT0]], [[TMP5]] ]
; CHECK-NEXT: ret i32 [[DOT1]]
;
store i32 5, i32* %0, align 4
@@ -52,13 +56,18 @@ define i32 @foo2(i32*, i32) {
; CHECK-NEXT: store i32 5, i32* [[TMP0:%.*]], align 4
; CHECK-NEXT: [[TMP3:%.*]] = icmp ne i32 [[TMP1:%.*]], 0
; CHECK-NEXT: br i1 [[TMP3]], label [[TMP4:%.*]], label [[TMP5:%.*]]
-; CHECK: br label [[TMP6:%.*]]
-; CHECK: br label [[TMP6]]
-; CHECK: [[PHIOFOPS:%.*]] = phi i32 [ 10, [[TMP5]] ], [ 15, [[TMP4]] ]
+; CHECK: 4:
+; CHECK-NEXT: br label [[TMP6:%.*]]
+; CHECK: 5:
+; CHECK-NEXT: br label [[TMP6]]
+; CHECK: 6:
; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ 10, [[TMP4]] ], [ 5, [[TMP5]] ]
-; CHECK-NEXT: br i1 [[TMP3]], label [[TMP7:%.*]], label [[TMP8:%.*]]
-; CHECK: br label [[TMP8]]
-; CHECK: [[DOT1:%.*]] = phi i32 [ [[PHIOFOPS]], [[TMP7]] ], [ [[DOT0]], [[TMP6]] ]
+; CHECK-NEXT: br i1 [[TMP3]], label [[TMP7:%.*]], label [[TMP9:%.*]]
+; CHECK: 7:
+; CHECK-NEXT: [[TMP8:%.*]] = add nsw i32 [[DOT0]], 5
+; CHECK-NEXT: br label [[TMP9]]
+; CHECK: 9:
+; CHECK-NEXT: [[DOT1:%.*]] = phi i32 [ [[TMP8]], [[TMP7]] ], [ [[DOT0]], [[TMP6]] ]
; CHECK-NEXT: ret i32 [[DOT1]]
;
store i32 5, i32* %0, align 4
generated by cgit v1.1 at 2025-10-17 17:07:07 +0000