[GVN] add early exit to ConstantFoldLoadThroughBitcast [NFC]

And adds some additional test coverage to ensure later commits don't
introduce regressions.

Differential Revision: https://reviews.llvm.org/D59730

diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index a414336..020c60c 100644 (file)
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -333,10 +333,15 @@ Constant *llvm::ConstantFoldLoadThroughBitcast(Constant *C, Type *DestTy,
                                          const DataLayout &DL) {
   do {
     Type *SrcTy = C->getType();
+    uint64_t DestSize = DL.getTypeSizeInBits(DestTy);
+    uint64_t SrcSize = DL.getTypeSizeInBits(SrcTy);
+    if (SrcSize < DestSize)
+      return nullptr;
 
     // If the type sizes are the same and a cast is legal, just directly
     // cast the constant.
-    if (DL.getTypeSizeInBits(DestTy) == DL.getTypeSizeInBits(SrcTy)) {
+    // But be careful not to coerce non-integral pointers illegally.
+    if (SrcSize == DestSize) {
       Instruction::CastOps Cast = Instruction::BitCast;
       // If we are going from a pointer to int or vice versa, we spell the cast
       // differently.

diff --git a/llvm/test/Transforms/GVN/non-integral-pointers.ll b/llvm/test/Transforms/GVN/non-integral-pointers.ll
index 2a5414f..133bc71 100644 (file)
--- a/llvm/test/Transforms/GVN/non-integral-pointers.ll
+++ b/llvm/test/Transforms/GVN/non-integral-pointers.ll
@@ -169,7 +169,14 @@ define i8 addrspace(4)* @forward_store_zero2(i8 addrspace(4)* addrspace(4)* %loc
   ret i8 addrspace(4)* %ref
 }
 
+
+
 @NonZeroConstant = constant <4 x i64> <i64 3, i64 3, i64 3, i64 3>
+@NonZeroConstant2 = constant <4 x i64 addrspace(4)*> <
+  i64 addrspace(4)* getelementptr (i64, i64 addrspace(4)* null, i32 3),
+  i64 addrspace(4)* getelementptr (i64, i64 addrspace(4)* null, i32 3),
+  i64 addrspace(4)* getelementptr (i64, i64 addrspace(4)* null, i32 3),
+  i64 addrspace(4)* getelementptr (i64, i64 addrspace(4)* null, i32 3)>
 @ZeroConstant = constant <4 x i64> zeroinitializer
 
 
@@ -190,6 +197,39 @@ entry:
   ret i8 addrspace(4)* %ref
 }
 
+define i64 addrspace(4)* @neg_forward_memcopy2(i64 addrspace(4)* addrspace(4)* %loc) {
+; CHECK-LABEL: @neg_forward_memcopy2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[LOC_BC:%.*]] = bitcast i64 addrspace(4)* addrspace(4)* [[LOC:%.*]] to i8 addrspace(4)*
+; CHECK-NEXT:    call void @llvm.memcpy.p4i8.p0i8.i64(i8 addrspace(4)* align 4 [[LOC_BC]], i8* bitcast (<4 x i64>* @NonZeroConstant to i8*), i64 8, i1 false)
+; CHECK-NEXT:    [[REF:%.*]] = load i64 addrspace(4)*, i64 addrspace(4)* addrspace(4)* [[LOC]]
+; CHECK-NEXT:    ret i64 addrspace(4)* [[REF]]
+;
+entry:
+  %loc.bc = bitcast i64 addrspace(4)* addrspace(4)* %loc to i8 addrspace(4)*
+  %src.bc = bitcast <4 x i64>* @NonZeroConstant to i8*
+  call void @llvm.memcpy.p4i8.p0i8.i64(i8 addrspace(4)* align 4 %loc.bc, i8* %src.bc, i64 8, i1 false)
+  %ref = load i64 addrspace(4)*, i64 addrspace(4)* addrspace(4)* %loc
+  ret i64 addrspace(4)* %ref
+}
+
+; TODO: missed optimization
+define i8 addrspace(4)* @forward_memcopy(i8 addrspace(4)* addrspace(4)* %loc) {
+; CHECK-LABEL: @forward_memcopy(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[LOC_BC:%.*]] = bitcast i8 addrspace(4)* addrspace(4)* [[LOC:%.*]] to i8 addrspace(4)*
+; CHECK-NEXT:    call void @llvm.memcpy.p4i8.p0i8.i64(i8 addrspace(4)* align 4 [[LOC_BC]], i8* bitcast (<4 x i64 addrspace(4)*>* @NonZeroConstant2 to i8*), i64 8, i1 false)
+; CHECK-NEXT:    [[REF:%.*]] = load i8 addrspace(4)*, i8 addrspace(4)* addrspace(4)* %loc
+; CHECK-NEXT:    ret i8 addrspace(4)* [[REF]]
+;
+entry:
+  %loc.bc = bitcast i8 addrspace(4)* addrspace(4)* %loc to i8 addrspace(4)*
+  %src.bc = bitcast <4 x i64 addrspace(4)*>* @NonZeroConstant2 to i8*
+  call void @llvm.memcpy.p4i8.p0i8.i64(i8 addrspace(4)* align 4 %loc.bc, i8* %src.bc, i64 8, i1 false)
+  %ref = load i8 addrspace(4)*, i8 addrspace(4)* addrspace(4)* %loc
+  ret i8 addrspace(4)* %ref
+}
+
 define <1 x i8 addrspace(4)*> @neg_forward_memcpy_vload(<1 x i8 addrspace(4)*> addrspace(4)* %loc) {
 ; CHECK-LABEL: @neg_forward_memcpy_vload(
 ; CHECK-NEXT:  entry:
@@ -206,6 +246,37 @@ entry:
   ret <1 x i8 addrspace(4)*> %ref
 }
 
+define <4 x i64 addrspace(4)*> @neg_forward_memcpy_vload2(<4 x i64 addrspace(4)*> addrspace(4)* %loc) {
+; CHECK-LABEL: @neg_forward_memcpy_vload2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[LOC_BC:%.*]] = bitcast <4 x i64 addrspace(4)*> addrspace(4)* [[LOC:%.*]] to i8 addrspace(4)*
+; CHECK-NEXT:    call void @llvm.memcpy.p4i8.p0i8.i64(i8 addrspace(4)* align 4 [[LOC_BC]], i8* bitcast (<4 x i64>* @NonZeroConstant to i8*), i64 32, i1 false)
+; CHECK-NEXT:    [[REF:%.*]] = load <4 x i64 addrspace(4)*>, <4 x i64 addrspace(4)*> addrspace(4)* [[LOC]]
+; CHECK-NEXT:    ret <4 x i64 addrspace(4)*> [[REF]]
+;
+entry:
+  %loc.bc = bitcast <4 x i64 addrspace(4)*> addrspace(4)* %loc to i8 addrspace(4)*
+  %src.bc = bitcast <4 x i64>* @NonZeroConstant to i8*
+  call void @llvm.memcpy.p4i8.p0i8.i64(i8 addrspace(4)* align 4 %loc.bc, i8* %src.bc, i64 32, i1 false)
+  %ref = load <4 x i64 addrspace(4)*>, <4 x i64 addrspace(4)*> addrspace(4)* %loc
+  ret <4 x i64 addrspace(4)*> %ref
+}
+
+define <4 x i64> @neg_forward_memcpy_vload3(<4 x i64> addrspace(4)* %loc) {
+; CHECK-LABEL: @neg_forward_memcpy_vload3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[LOC_BC:%.*]] = bitcast <4 x i64> addrspace(4)* [[LOC:%.*]] to i8 addrspace(4)*
+; CHECK-NEXT:    call void @llvm.memcpy.p4i8.p0i8.i64(i8 addrspace(4)* align 4 [[LOC_BC]], i8* bitcast (<4 x i64 addrspace(4)*>* @NonZeroConstant2 to i8*), i64 32, i1 false)
+; CHECK-NEXT:    [[REF:%.*]] = load <4 x i64>, <4 x i64> addrspace(4)* [[LOC]]
+; CHECK-NEXT:    ret <4 x i64> [[REF]]
+;
+entry:
+  %loc.bc = bitcast <4 x i64> addrspace(4)* %loc to i8 addrspace(4)*
+  %src.bc = bitcast <4 x i64 addrspace(4)*>* @NonZeroConstant2 to i8*
+  call void @llvm.memcpy.p4i8.p0i8.i64(i8 addrspace(4)* align 4 %loc.bc, i8* %src.bc, i64 32, i1 false)
+  %ref = load <4 x i64>, <4 x i64> addrspace(4)* %loc
+  ret <4 x i64> %ref
+}
 
 ; Can forward since we can do so w/o breaking types
 ; TODO: missed optimization

diff --git a/llvm/test/Transforms/GlobalOpt/evaluate-call-errors.ll b/llvm/test/Transforms/GlobalOpt/evaluate-call-errors.ll
index 88f7cbd..84fe70b 100644 (file)
--- a/llvm/test/Transforms/GlobalOpt/evaluate-call-errors.ll
+++ b/llvm/test/Transforms/GlobalOpt/evaluate-call-errors.ll
@@ -65,7 +65,7 @@ define linkonce_odr void @_ZN1SC2Ev(%struct.S*) unnamed_addr align 2 {
 }
 
 define internal %struct.Foo* @_ZL3foov() {
-  ret %struct.Foo* null
+  ret %struct.Foo* getelementptr (%struct.Foo, %struct.Foo *null, i32 1)
 }
 
 define linkonce_odr void @_ZN1QC2Ev(%struct.Q*) unnamed_addr align 2 {
@@ -73,7 +73,7 @@ define linkonce_odr void @_ZN1QC2Ev(%struct.Q*) unnamed_addr align 2 {
   store %struct.Q* %0, %struct.Q** %2, align 8
   %3 = load %struct.Q*, %struct.Q** %2, align 8
   %4 = getelementptr inbounds %struct.Q, %struct.Q* %3, i32 0, i32 0
-  %5 = call i32 bitcast (i32 (i32)* @_ZL3baz3Foo to i32 (%struct.Foo*)*)(%struct.Foo* null)
+  %5 = call i32 bitcast (i32 (i32)* @_ZL3baz3Foo to i32 (%struct.Foo*)*)(%struct.Foo* getelementptr (%struct.Foo, %struct.Foo *null, i32 1))
   store i32 %5, i32* %4, align 4
   ret void
 }