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-rw-r--r--llvm/lib/Analysis/ValueTracking.cpp48
-rw-r--r--llvm/test/Transforms/MemCpyOpt/store-to-memset.ll77
2 files changed, 116 insertions, 9 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index f0b87810ef9..aaebba00527 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -5755,17 +5755,47 @@ Optional<int64_t> llvm::isPointerOffset(const Value *Ptr1, const Value *Ptr2,
const GEPOperator *GEP1 = dyn_cast<GEPOperator>(Ptr1);
const GEPOperator *GEP2 = dyn_cast<GEPOperator>(Ptr2);
- // If one pointer is a GEP and the other isn't, then see if the GEP is a
- // constant offset from the base, as in "P" and "gep P, 1".
- if (GEP1 && !GEP2 && GEP1->getOperand(0)->stripPointerCasts() == Ptr2) {
- auto Offset = getOffsetFromIndex(GEP1, 1, DL);
- if (!Offset)
+ // If one pointer is a GEP see if the GEP is a constant offset from the base,
+ // as in "P" and "gep P, 1".
+ // Also do this iteratively to handle the the following case:
+ // Ptr_t1 = GEP Ptr1, c1
+ // Ptr_t2 = GEP Ptr_t1, c2
+ // Ptr2 = GEP Ptr_t2, c3
+ // where we will return c1+c2+c3.
+ // TODO: Handle the case when both Ptr1 and Ptr2 are GEPs of some common base
+ // -- replace getOffsetFromBase with getOffsetAndBase, check that the bases
+ // are the same, and return the difference between offsets.
+ auto getOffsetFromBase = [&DL](const GEPOperator *GEP,
+ const Value *Ptr) -> Optional<int64_t> {
+ const GEPOperator *GEP_T = GEP;
+ int64_t OffsetVal = 0;
+ bool HasSameBase = false;
+ while (GEP_T) {
+ auto Offset = getOffsetFromIndex(GEP_T, 1, DL);
+ if (!Offset)
+ return None;
+ OffsetVal += *Offset;
+ auto Op0 = GEP_T->getOperand(0)->stripPointerCasts();
+ if (Op0 == Ptr) {
+ HasSameBase = true;
+ break;
+ }
+ GEP_T = dyn_cast<GEPOperator>(Op0);
+ }
+ if (!HasSameBase)
return None;
- return -*Offset;
- }
+ return OffsetVal;
+ };
- if (GEP2 && !GEP1 && GEP2->getOperand(0)->stripPointerCasts() == Ptr1) {
- return getOffsetFromIndex(GEP2, 1, DL);
+ if (GEP1) {
+ auto Offset = getOffsetFromBase(GEP1, Ptr2);
+ if (Offset)
+ return -*Offset;
+ }
+ if (GEP2) {
+ auto Offset = getOffsetFromBase(GEP2, Ptr1);
+ if (Offset)
+ return Offset;
}
// Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical
diff --git a/llvm/test/Transforms/MemCpyOpt/store-to-memset.ll b/llvm/test/Transforms/MemCpyOpt/store-to-memset.ll
new file mode 100644
index 00000000000..59ed892b60e
--- /dev/null
+++ b/llvm/test/Transforms/MemCpyOpt/store-to-memset.ll
@@ -0,0 +1,77 @@
+; RUN: opt < %s -memcpyopt -S | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+define i8* @foo(i8* returned %0, i32 %1, i64 %2) {
+entry:
+ %3 = getelementptr inbounds i8, i8* %0, i64 %2
+ %4 = getelementptr inbounds i8, i8* %3, i64 -32
+ %vv = trunc i32 %1 to i8
+ store i8 %vv, i8* %4, align 1
+ %5 = getelementptr inbounds i8, i8* %4, i64 1
+ store i8 %vv, i8* %5, align 1
+ %6= getelementptr inbounds i8, i8* %4, i64 2
+ store i8 %vv, i8* %6, align 1
+ %7= getelementptr inbounds i8, i8* %4, i64 3
+ store i8 %vv, i8* %7, align 1
+ %8= getelementptr inbounds i8, i8* %4, i64 4
+ store i8 %vv, i8* %8, align 1
+ %9= getelementptr inbounds i8, i8* %4, i64 5
+ store i8 %vv, i8* %9, align 1
+ %10= getelementptr inbounds i8, i8* %4, i64 6
+ store i8 %vv, i8* %10, align 1
+ %11= getelementptr inbounds i8, i8* %4, i64 7
+ store i8 %vv, i8* %11, align 1
+ %12= getelementptr inbounds i8, i8* %4, i64 8
+ store i8 %vv, i8* %12, align 1
+ %13= getelementptr inbounds i8, i8* %4, i64 9
+ store i8 %vv, i8* %13, align 1
+ %14= getelementptr inbounds i8, i8* %4, i64 10
+ store i8 %vv, i8* %14, align 1
+ %15= getelementptr inbounds i8, i8* %4, i64 11
+ store i8 %vv, i8* %15, align 1
+ %16= getelementptr inbounds i8, i8* %4, i64 12
+ store i8 %vv, i8* %16, align 1
+ %17= getelementptr inbounds i8, i8* %4, i64 13
+ store i8 %vv, i8* %17, align 1
+ %18= getelementptr inbounds i8, i8* %4, i64 14
+ store i8 %vv, i8* %18, align 1
+ %19= getelementptr inbounds i8, i8* %4, i64 15
+ store i8 %vv, i8* %19, align 1
+ %20= getelementptr inbounds i8, i8* %4, i64 16
+ store i8 %vv, i8* %20, align 1
+ %21= getelementptr inbounds i8, i8* %20, i64 1
+ store i8 %vv, i8* %21, align 1
+ %22= getelementptr inbounds i8, i8* %20, i64 2
+ store i8 %vv, i8* %22, align 1
+ %23= getelementptr inbounds i8, i8* %20, i64 3
+ store i8 %vv, i8* %23, align 1
+ %24= getelementptr inbounds i8, i8* %20, i64 4
+ store i8 %vv, i8* %24, align 1
+ %25= getelementptr inbounds i8, i8* %20, i64 5
+ store i8 %vv, i8* %25, align 1
+ %26= getelementptr inbounds i8, i8* %20, i64 6
+ store i8 %vv, i8* %26, align 1
+ %27= getelementptr inbounds i8, i8* %20, i64 7
+ store i8 %vv, i8* %27, align 1
+ %28= getelementptr inbounds i8, i8* %20, i64 8
+ store i8 %vv, i8* %28, align 1
+ %29= getelementptr inbounds i8, i8* %20, i64 9
+ store i8 %vv, i8* %29, align 1
+ %30= getelementptr inbounds i8, i8* %20, i64 10
+ store i8 %vv, i8* %30, align 1
+ %31 = getelementptr inbounds i8, i8* %20, i64 11
+ store i8 %vv, i8* %31, align 1
+ %32 = getelementptr inbounds i8, i8* %20, i64 12
+ store i8 %vv, i8* %32, align 1
+ %33 = getelementptr inbounds i8, i8* %20, i64 13
+ store i8 %vv, i8* %33, align 1
+ %34 = getelementptr inbounds i8, i8* %20, i64 14
+ store i8 %vv, i8* %34, align 1
+ %35 = getelementptr inbounds i8, i8* %20, i64 15
+ store i8 %vv, i8* %35, align 1
+ ret i8* %0
+; CHECK-LABEL: @foo
+; CHECK: call void @llvm.memset.p0i8.i64(i8* align 1 %4, i8 %vv, i64 32, i1 false)
+}
+
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