641 changes: 641 additions & 0 deletions llvm/lib/Transforms/Scalar/MergeICmps.cpp
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1 change: 1 addition & 0 deletions llvm/lib/Transforms/Scalar/Scalar.cpp
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Expand Up @@ -73,6 +73,7 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
initializeLowerExpectIntrinsicPass(Registry);
initializeLowerGuardIntrinsicLegacyPassPass(Registry);
initializeMemCpyOptLegacyPassPass(Registry);
initializeMergeICmpsPass(Registry);
initializeMergedLoadStoreMotionLegacyPassPass(Registry);
initializeNaryReassociateLegacyPassPass(Registry);
initializePartiallyInlineLibCallsLegacyPassPass(Registry);
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87 changes: 87 additions & 0 deletions llvm/test/Transforms/MergeICmps/pair-int32-int32.ll
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; RUN: opt -mergeicmps -S -o - %s | FileCheck %s

%"struct.std::pair" = type { i32, i32 }

define zeroext i1 @opeq1(
%"struct.std::pair"* nocapture readonly dereferenceable(8) %a,
%"struct.std::pair"* nocapture readonly dereferenceable(8) %b) local_unnamed_addr #0 {
entry:
%first.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 0
%0 = load i32, i32* %first.i, align 4
%first1.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 0
%1 = load i32, i32* %first1.i, align 4
%cmp.i = icmp eq i32 %0, %1
br i1 %cmp.i, label %land.rhs.i, label %opeq1.exit

land.rhs.i:
%second.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 1
%2 = load i32, i32* %second.i, align 4
%second2.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 1
%3 = load i32, i32* %second2.i, align 4
%cmp3.i = icmp eq i32 %2, %3
br label %opeq1.exit

opeq1.exit:
%4 = phi i1 [ false, %entry ], [ %cmp3.i, %land.rhs.i ]
ret i1 %4
; CHECK-LABEL: @opeq1(
; The entry block with zero-offset GEPs is kept, loads are removed.
; CHECK: entry
; CHECK: getelementptr {{.*}} i32 0
; CHECK-NOT: load
; CHECK: getelementptr {{.*}} i32 0
; CHECK-NOT: load
; The two 4 byte loads and compares are replaced with a single 8-byte memcmp.
; CHECK: @memcmp({{.*}}8)
; CHECK: icmp eq {{.*}} 0
; The branch is now a direct branch; the other block has been removed.
; CHECK: br label %opeq1.exit
; CHECK-NOT: br
; The phi is updated.
; CHECK: phi i1 [ %{{[^,]*}}, %entry ]
; CHECK-NEXT: ret
}

; Same as above, but the two blocks are in inverse order.
define zeroext i1 @opeq1_inverse(
%"struct.std::pair"* nocapture readonly dereferenceable(8) %a,
%"struct.std::pair"* nocapture readonly dereferenceable(8) %b) local_unnamed_addr #0 {
entry:
%first.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 1
%0 = load i32, i32* %first.i, align 4
%first1.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 1
%1 = load i32, i32* %first1.i, align 4
%cmp.i = icmp eq i32 %0, %1
br i1 %cmp.i, label %land.rhs.i, label %opeq1.exit

land.rhs.i:
%second.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 0
%2 = load i32, i32* %second.i, align 4
%second2.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 0
%3 = load i32, i32* %second2.i, align 4
%cmp3.i = icmp eq i32 %2, %3
br label %opeq1.exit

opeq1.exit:
%4 = phi i1 [ false, %entry ], [ %cmp3.i, %land.rhs.i ]
ret i1 %4
; CHECK-LABEL: @opeq1_inverse(
; The second block with zero-offset GEPs is kept, loads are removed.
; CHECK: land.rhs.i
; CHECK: getelementptr {{.*}} i32 0
; CHECK-NOT: load
; CHECK: getelementptr {{.*}} i32 0
; CHECK-NOT: load
; The two 4 byte loads and compares are replaced with a single 8-byte memcmp.
; CHECK: @memcmp({{.*}}8)
; CHECK: icmp eq {{.*}} 0
; The branch is now a direct branch; the other block has been removed.
; CHECK: br label %opeq1.exit
; CHECK-NOT: br
; The phi is updated.
; CHECK: phi i1 [ %{{[^,]*}}, %land.rhs.i ]
; CHECK-NEXT: ret
}



73 changes: 73 additions & 0 deletions llvm/test/Transforms/MergeICmps/tuple-four-int8.ll
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; RUN: opt -mergeicmps -S -o - %s | FileCheck %s

; This is a more involved test: clang generates this weird pattern for
; tuple<uint8_t, uint8_t, uint8_t, uint8_t>. Right now we skip the entry block
; (which defines the base pointer for other blocks) and the last one (which
; does not have the expected structure). Only middle blocks (bytes [1,2]) are
; merged.

%"class.std::tuple" = type { %"struct.std::_Tuple_impl" }
%"struct.std::_Tuple_impl" = type { %"struct.std::_Tuple_impl.0", %"struct.std::_Head_base.6" }
%"struct.std::_Tuple_impl.0" = type { %"struct.std::_Tuple_impl.1", %"struct.std::_Head_base.5" }
%"struct.std::_Tuple_impl.1" = type { %"struct.std::_Tuple_impl.2", %"struct.std::_Head_base.4" }
%"struct.std::_Tuple_impl.2" = type { %"struct.std::_Head_base" }
%"struct.std::_Head_base" = type { i8 }
%"struct.std::_Head_base.4" = type { i8 }
%"struct.std::_Head_base.5" = type { i8 }
%"struct.std::_Head_base.6" = type { i8 }

define zeroext i1 @opeq(
%"class.std::tuple"* nocapture readonly dereferenceable(4) %a,
%"class.std::tuple"* nocapture readonly dereferenceable(4) %b) local_unnamed_addr #1 {
entry:
%0 = getelementptr inbounds %"class.std::tuple", %"class.std::tuple"* %a, i64 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0
%add.ptr.i.i.i.i.i = getelementptr inbounds i8, i8* %0, i64 3
%1 = load i8, i8* %add.ptr.i.i.i.i.i, align 1
%2 = getelementptr inbounds %"class.std::tuple", %"class.std::tuple"* %b, i64 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0
%add.ptr.i.i.i6.i.i = getelementptr inbounds i8, i8* %2, i64 3
%3 = load i8, i8* %add.ptr.i.i.i6.i.i, align 1
%cmp.i.i = icmp eq i8 %1, %3
br i1 %cmp.i.i, label %land.rhs.i.i, label %opeq.exit

land.rhs.i.i:
%add.ptr.i.i.i.i.i.i = getelementptr inbounds i8, i8* %0, i64 2
%4 = load i8, i8* %add.ptr.i.i.i.i.i.i, align 1
%add.ptr.i.i.i6.i.i.i = getelementptr inbounds i8, i8* %2, i64 2
%5 = load i8, i8* %add.ptr.i.i.i6.i.i.i, align 1
%cmp.i.i.i = icmp eq i8 %4, %5
br i1 %cmp.i.i.i, label %land.rhs.i.i.i, label %opeq.exit

land.rhs.i.i.i:
%add.ptr.i.i.i.i.i.i.i = getelementptr inbounds i8, i8* %0, i64 1
%6 = load i8, i8* %add.ptr.i.i.i.i.i.i.i, align 1
%add.ptr.i.i.i6.i.i.i.i = getelementptr inbounds i8, i8* %2, i64 1
%7 = load i8, i8* %add.ptr.i.i.i6.i.i.i.i, align 1
%cmp.i.i.i.i = icmp eq i8 %6, %7
br i1 %cmp.i.i.i.i, label %land.rhs.i.i.i.i, label %opeq.exit

land.rhs.i.i.i.i:
%8 = load i8, i8* %0, align 1
%9 = load i8, i8* %2, align 1
%cmp.i.i.i.i.i = icmp eq i8 %8, %9
br label %opeq.exit

opeq.exit:
%10 = phi i1 [ false, %entry ], [ false, %land.rhs.i.i ], [ false, %land.rhs.i.i.i ], [ %cmp.i.i.i.i.i, %land.rhs.i.i.i.i ]
ret i1 %10
; CHECK-LABEL: @opeq(
; The entry block is kept as is, but the next block is now the merged comparison
; block for bytes [1,2] or the block for the head.
; CHECK: entry
; CHECK: br i1 %cmp.i.i, label %land.rhs.i.i.i{{(.i)?}}, label %opeq.exit
; The two 1 byte loads and compares at offset 1 are replaced with a single
; 2-byte memcmp.
; CHECK: land.rhs.i.i.i
; CHECK: @memcmp({{.*}}2)
; CHECK: icmp eq {{.*}} 0
; In the end we have three blocks.
; CHECK: phi i1
; CHECK-SAME %entry
; CHECK-SAME %land.rhs.i.i.i.i
; CHECK-SAME %land.rhs.i.i.i
}

30 changes: 30 additions & 0 deletions llvm/test/Transforms/MergeICmps/volatile.ll
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; RUN: opt -mergeicmps -S -o - %s | FileCheck %s

%"struct.std::pair" = type { i32, i32 }

define zeroext i1 @opeq(
%"struct.std::pair"* nocapture readonly dereferenceable(8) %a,
%"struct.std::pair"* nocapture readonly dereferenceable(8) %b) local_unnamed_addr #0 {
entry:
%first.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 0
%0 = load i32, i32* %first.i, align 4
%first1.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 0
%1 = load i32, i32* %first1.i, align 4
%cmp.i = icmp eq i32 %0, %1
br i1 %cmp.i, label %land.rhs.i, label %opeq1.exit

land.rhs.i:
%second.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 1
%2 = load volatile i32, i32* %second.i, align 4
%second2.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 1
%3 = load i32, i32* %second2.i, align 4
%cmp3.i = icmp eq i32 %2, %3
br label %opeq1.exit

opeq1.exit:
%4 = phi i1 [ false, %entry ], [ %cmp3.i, %land.rhs.i ]
ret i1 %4
; CHECK-LABEL: @opeq(
; CHECK-NOT: memcmp
}