f1106ef6c9
We try to fold constant computeKnownBits() with context for return instructions only. Otherwise, we rely on SimplifyDemandedBits() to fold instructions with constant known bits. The presence of this special fold for returns is dangerous, because it makes our tests lie about what works and what doesn't. Tests are usually written by returning the result we're interested in, but will go through this separate code path that is not used for anything else. This patch removes the special fold. This primarily regresses patterns of the style "assume(x); return x". The responsibility of handling such patterns lies with passes like EarlyCSE/GVN anyway, which will do this reliably, and not just for returns. Differential Revision: https://reviews.llvm.org/D151099
211 lines
6.0 KiB
LLVM
211 lines
6.0 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -S -passes=instcombine < %s | FileCheck %s
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;
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; Tests to show cases where computeKnownBits should be able to determine
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; the known bits of a phi edge based off a conditional branch feeding the phi.
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;
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; %x either eq 7 or is set to 7
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define i64 @limit_i64_eq_7(i64 %x) {
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; CHECK-LABEL: @limit_i64_eq_7(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[X:%.*]], 7
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; CHECK-NEXT: br i1 [[CMP]], label [[END:%.*]], label [[BODY:%.*]]
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; CHECK: body:
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; CHECK-NEXT: br label [[END]]
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; CHECK: end:
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; CHECK-NEXT: [[RES:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ 7, [[BODY]] ]
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; CHECK-NEXT: ret i64 [[RES]]
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;
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entry:
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%cmp = icmp eq i64 %x, 7
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br i1 %cmp, label %end, label %body
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body:
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br label %end
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end:
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%res = phi i64 [ %x, %entry ], [ 7, %body ]
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ret i64 %res
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}
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; %x either eq 255 or is set to 255
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define i64 @limit_i64_ne_255(i64 %x) {
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; CHECK-LABEL: @limit_i64_ne_255(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp ne i64 [[X:%.*]], 255
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; CHECK-NEXT: call void @use(i1 [[CMP]])
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; CHECK-NEXT: br i1 [[CMP]], label [[BODY:%.*]], label [[END:%.*]]
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; CHECK: body:
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; CHECK-NEXT: br label [[END]]
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; CHECK: end:
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; CHECK-NEXT: [[RES:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ 255, [[BODY]] ]
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; CHECK-NEXT: ret i64 [[RES]]
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;
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entry:
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%cmp = icmp ne i64 %x, 255
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call void @use(i1 %cmp)
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br i1 %cmp, label %body, label %end
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body:
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br label %end
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end:
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%res = phi i64 [ %x, %entry ], [ 255, %body ]
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ret i64 %res
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}
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declare void @use(i1)
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; %x either ule 15 or is masked with 15
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define i64 @limit_i64_ule_15(i64 %x) {
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; CHECK-LABEL: @limit_i64_ule_15(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[X:%.*]], 16
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; CHECK-NEXT: br i1 [[CMP]], label [[END:%.*]], label [[BODY:%.*]]
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; CHECK: body:
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; CHECK-NEXT: [[MASK:%.*]] = and i64 [[X]], 15
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; CHECK-NEXT: br label [[END]]
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; CHECK: end:
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; CHECK-NEXT: [[X_MASK:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ [[MASK]], [[BODY]] ]
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; CHECK-NEXT: ret i64 [[X_MASK]]
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;
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entry:
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%cmp = icmp ule i64 %x, 15
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br i1 %cmp, label %end, label %body
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body:
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%mask = and i64 %x, 15
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br label %end
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end:
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%x.mask = phi i64 [ %x, %entry ], [ %mask, %body ]
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%res = and i64 %x.mask, 15
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ret i64 %res
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}
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; %x either uge 8 or is masked with 7
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define i64 @limit_i64_uge_8(i64 %x) {
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; CHECK-LABEL: @limit_i64_uge_8(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X:%.*]], 7
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; CHECK-NEXT: br i1 [[CMP]], label [[BODY:%.*]], label [[END:%.*]]
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; CHECK: body:
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; CHECK-NEXT: [[MASK:%.*]] = and i64 [[X]], 7
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; CHECK-NEXT: br label [[END]]
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; CHECK: end:
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; CHECK-NEXT: [[X_MASK:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ [[MASK]], [[BODY]] ]
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; CHECK-NEXT: ret i64 [[X_MASK]]
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;
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entry:
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%cmp = icmp uge i64 %x, 8
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br i1 %cmp, label %body, label %end
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body:
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%mask = and i64 %x, 7
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br label %end
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end:
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%x.mask = phi i64 [ %x, %entry ], [ %mask, %body ]
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%res = and i64 %x.mask, 7
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ret i64 %res
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}
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; %x either ult 8 or is masked with 7
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define i64 @limit_i64_ult_8(i64 %x) {
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; CHECK-LABEL: @limit_i64_ult_8(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[X:%.*]], 8
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; CHECK-NEXT: br i1 [[CMP]], label [[END:%.*]], label [[BODY:%.*]]
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; CHECK: body:
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; CHECK-NEXT: [[MASK:%.*]] = and i64 [[X]], 7
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; CHECK-NEXT: br label [[END]]
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; CHECK: end:
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; CHECK-NEXT: [[X_MASK:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ [[MASK]], [[BODY]] ]
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; CHECK-NEXT: ret i64 [[X_MASK]]
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;
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entry:
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%cmp = icmp ult i64 %x, 8
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br i1 %cmp, label %end, label %body
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body:
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%mask = and i64 %x, 7
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br label %end
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end:
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%x.mask = phi i64 [ %x, %entry ], [ %mask, %body ]
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%res = and i64 %x.mask, 7
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ret i64 %res
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}
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; %x either ugt 7 or is masked with 7
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define i64 @limit_i64_ugt_7(i64 %x) {
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; CHECK-LABEL: @limit_i64_ugt_7(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X:%.*]], 7
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; CHECK-NEXT: br i1 [[CMP]], label [[BODY:%.*]], label [[END:%.*]]
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; CHECK: body:
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; CHECK-NEXT: [[MASK:%.*]] = and i64 [[X]], 7
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; CHECK-NEXT: br label [[END]]
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; CHECK: end:
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; CHECK-NEXT: [[X_MASK:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ [[MASK]], [[BODY]] ]
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; CHECK-NEXT: ret i64 [[X_MASK]]
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;
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entry:
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%cmp = icmp ugt i64 %x, 7
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br i1 %cmp, label %body, label %end
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body:
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%mask = and i64 %x, 7
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br label %end
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end:
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%x.mask = phi i64 [ %x, %entry ], [ %mask, %body ]
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%res = and i64 %x.mask, 7
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ret i64 %res
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}
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;
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; negative tests
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;
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; %x either ule 15 or is masked with 15
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define i64 @limit_i64_ule_15_mask3(i64 %x) {
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; CHECK-LABEL: @limit_i64_ule_15_mask3(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[X:%.*]], 16
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; CHECK-NEXT: br i1 [[CMP]], label [[END:%.*]], label [[BODY:%.*]]
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; CHECK: body:
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; CHECK-NEXT: [[MASK:%.*]] = and i64 [[X]], 15
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; CHECK-NEXT: br label [[END]]
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; CHECK: end:
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; CHECK-NEXT: [[X_MASK:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ [[MASK]], [[BODY]] ]
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; CHECK-NEXT: [[RES:%.*]] = and i64 [[X_MASK]], 3
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; CHECK-NEXT: ret i64 [[RES]]
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;
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entry:
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%cmp = icmp ule i64 %x, 15
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br i1 %cmp, label %end, label %body
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body:
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%mask = and i64 %x, 15
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br label %end
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end:
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%x.mask = phi i64 [ %x, %entry ], [ %mask, %body ]
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%res = and i64 %x.mask, 3
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ret i64 %res
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}
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; %x either ult 8 or is masked with 7
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define i64 @limit_i64_ult_8_mask1(i64 %x) {
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; CHECK-LABEL: @limit_i64_ult_8_mask1(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[X:%.*]], 8
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; CHECK-NEXT: br i1 [[CMP]], label [[END:%.*]], label [[BODY:%.*]]
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; CHECK: body:
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; CHECK-NEXT: [[MASK:%.*]] = and i64 [[X]], 7
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; CHECK-NEXT: br label [[END]]
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; CHECK: end:
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; CHECK-NEXT: [[X_MASK:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ [[MASK]], [[BODY]] ]
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; CHECK-NEXT: [[RES:%.*]] = and i64 [[X_MASK]], 1
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; CHECK-NEXT: ret i64 [[RES]]
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;
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entry:
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%cmp = icmp ult i64 %x, 8
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br i1 %cmp, label %end, label %body
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body:
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%mask = and i64 %x, 7
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br label %end
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end:
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%x.mask = phi i64 [ %x, %entry ], [ %mask, %body ]
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%res = and i64 %x.mask, 1
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ret i64 %res
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}
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