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[DA] Check nsw when extracting a constant operand of SCEVMul
1 parent 7444b19 commit bd44388

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4 files changed

+14
-16
lines changed

4 files changed

+14
-16
lines changed

‎llvm/lib/Analysis/DependenceAnalysis.cpp‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2828,8 +2828,9 @@ static std::optional<APInt> getConstantPart(const SCEV *Expr) {
28282828
if (const auto *Constant = dyn_cast<SCEVConstant>(Expr))
28292829
return Constant->getAPInt();
28302830
if (const auto *Product = dyn_cast<SCEVMulExpr>(Expr))
2831-
if (const auto *Constant = dyn_cast<SCEVConstant>(Product->getOperand(0)))
2832-
return Constant->getAPInt();
2831+
if (Product->hasNoSignedWrap())
2832+
if (auto *Constant = dyn_cast<SCEVConstant>(Product->getOperand(0)))
2833+
return Constant->getAPInt();
28332834
return std::nullopt;
28342835
}
28352836

‎llvm/test/Analysis/DependenceAnalysis/GCD.ll‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -254,7 +254,7 @@ define void @gcd4(ptr %A, ptr %B, i64 %M, i64 %N) nounwind uwtable ssp {
254254
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %conv, ptr %arrayidx, align 4
255255
; CHECK-NEXT: da analyze - output [* *]!
256256
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: %0 = load i32, ptr %arrayidx16, align 4
257-
; CHECK-NEXT: da analyze - none!
257+
; CHECK-NEXT: da analyze - flow [* *|<]!
258258
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %0, ptr %B.addr.11, align 4
259259
; CHECK-NEXT: da analyze - confused!
260260
; CHECK-NEXT: Src: %0 = load i32, ptr %arrayidx16, align 4 --> Dst: %0 = load i32, ptr %arrayidx16, align 4
@@ -322,7 +322,7 @@ define void @gcd5(ptr %A, ptr %B, i64 %M, i64 %N) nounwind uwtable ssp {
322322
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %conv, ptr %arrayidx, align 4
323323
; CHECK-NEXT: da analyze - output [* *]!
324324
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: %0 = load i32, ptr %arrayidx16, align 4
325-
; CHECK-NEXT: da analyze - flow [<> *]!
325+
; CHECK-NEXT: da analyze - flow [* *|<]!
326326
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %0, ptr %B.addr.11, align 4
327327
; CHECK-NEXT: da analyze - confused!
328328
; CHECK-NEXT: Src: %0 = load i32, ptr %arrayidx16, align 4 --> Dst: %0 = load i32, ptr %arrayidx16, align 4
@@ -390,7 +390,7 @@ define void @gcd6(i64 %n, ptr %A, ptr %B) nounwind uwtable ssp {
390390
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx5, align 4 --> Dst: store i32 %conv, ptr %arrayidx5, align 4
391391
; CHECK-NEXT: da analyze - output [* *]!
392392
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx5, align 4 --> Dst: %2 = load i32, ptr %arrayidx9, align 4
393-
; CHECK-NEXT: da analyze - none!
393+
; CHECK-NEXT: da analyze - flow [* *|<]!
394394
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx5, align 4 --> Dst: store i32 %2, ptr %B.addr.12, align 4
395395
; CHECK-NEXT: da analyze - confused!
396396
; CHECK-NEXT: Src: %2 = load i32, ptr %arrayidx9, align 4 --> Dst: %2 = load i32, ptr %arrayidx9, align 4

‎llvm/test/Analysis/DependenceAnalysis/SymbolicSIV.ll‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -384,7 +384,7 @@ define void @symbolicsiv6(ptr %A, ptr %B, i64 %n, i64 %N, i64 %M) nounwind uwtab
384384
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %conv, ptr %arrayidx, align 4
385385
; CHECK-NEXT: da analyze - none!
386386
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: %0 = load i32, ptr %arrayidx7, align 4
387-
; CHECK-NEXT: da analyze - none!
387+
; CHECK-NEXT: da analyze - flow [*|<]!
388388
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %0, ptr %B.addr.02, align 4
389389
; CHECK-NEXT: da analyze - confused!
390390
; CHECK-NEXT: Src: %0 = load i32, ptr %arrayidx7, align 4 --> Dst: %0 = load i32, ptr %arrayidx7, align 4
@@ -440,7 +440,7 @@ define void @symbolicsiv7(ptr %A, ptr %B, i64 %n, i64 %N, i64 %M) nounwind uwtab
440440
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %conv, ptr %arrayidx, align 4
441441
; CHECK-NEXT: da analyze - none!
442442
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: %1 = load i32, ptr %arrayidx6, align 4
443-
; CHECK-NEXT: da analyze - flow [<>]!
443+
; CHECK-NEXT: da analyze - flow [*|<]!
444444
; CHECK-NEXT: Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %1, ptr %B.addr.02, align 4
445445
; CHECK-NEXT: da analyze - confused!
446446
; CHECK-NEXT: Src: %1 = load i32, ptr %arrayidx6, align 4 --> Dst: %1 = load i32, ptr %arrayidx6, align 4

‎llvm/test/Analysis/DependenceAnalysis/gcd-miv-overflow.ll‎

Lines changed: 6 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -13,31 +13,28 @@
1313
; offset1 += 3;
1414
; }
1515
;
16-
; FIXME: DependenceAnalysis currently detects no dependency between the two
17-
; stores, but it does exist. E.g., consider `m` is 12297829382473034411, which
18-
; is a modular multiplicative inverse of 3 under modulo 2^64. Then `offset0` is
19-
; effectively `i + 4`, so accesses will be as follows:
16+
; Dependency exists between the two stores. E.g., consider `m` is
17+
; 12297829382473034411, which is a modular multiplicative inverse of 3 under
18+
; modulo 2^64. Then `offset0` is effectively `i + 4`, so accesses will be as
19+
; follows:
2020
;
2121
; - A[offset0] : A[4], A[5], A[6], ...
2222
; - A[offset1] : A[0], A[3], A[6], ...
2323
;
24-
; The root cause is that DA assumes `3*m` begin a multiple of 3 in mathematical
25-
; sense, which isn't necessarily true due to overflow.
26-
;
2724
define void @gcdmiv_coef_ovfl(ptr %A, i64 %m) {
2825
; CHECK-ALL-LABEL: 'gcdmiv_coef_ovfl'
2926
; CHECK-ALL-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1
3027
; CHECK-ALL-NEXT: da analyze - none!
3128
; CHECK-ALL-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1
32-
; CHECK-ALL-NEXT: da analyze - none!
29+
; CHECK-ALL-NEXT: da analyze - output [*|<]!
3330
; CHECK-ALL-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1
3431
; CHECK-ALL-NEXT: da analyze - none!
3532
;
3633
; CHECK-GCD-MIV-LABEL: 'gcdmiv_coef_ovfl'
3734
; CHECK-GCD-MIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.0, align 1
3835
; CHECK-GCD-MIV-NEXT: da analyze - consistent output [*]!
3936
; CHECK-GCD-MIV-NEXT: Src: store i8 1, ptr %gep.0, align 1 --> Dst: store i8 2, ptr %gep.1, align 1
40-
; CHECK-GCD-MIV-NEXT: da analyze - none!
37+
; CHECK-GCD-MIV-NEXT: da analyze - consistent output [*|<]!
4138
; CHECK-GCD-MIV-NEXT: Src: store i8 2, ptr %gep.1, align 1 --> Dst: store i8 2, ptr %gep.1, align 1
4239
; CHECK-GCD-MIV-NEXT: da analyze - consistent output [*]!
4340
;

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