734ee0e01f
Currently, LVI will only use conditions like "X < C" to constrain the value of X on the relevant edge. This patch extends it to handle conditions like "X < Y" by querying the known range of Y. This means that getValueFromCondition() and various related APIs can now return nullopt to indicate that they have pushed to the worklist, and need to be called again later. This behavior is currently controlled by a UseBlockValue option, and only enabled for actual edge value handling. All other places deriving constraints from conditions keep using the previous logic for now. This change was originally motivated as a fix for the regression reported in https://github.com/llvm/llvm-project/pull/73662#issuecomment-1849281758. Unfortunately, it doesn't actually fix it, because we run into another issue there (LVI currently is really bad at handling values used in loops). This change has some compile-time impact, but it's fairly small, in the 0.05% range.
97 lines
2.7 KiB
LLVM
97 lines
2.7 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
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; RUN: opt -S -passes=correlated-propagation < %s | FileCheck %s
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declare void @use(i1)
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define void @test_icmp_from_implied_cond(i32 %a, i32 %b) {
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; CHECK-LABEL: define void @test_icmp_from_implied_cond(
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; CHECK-SAME: i32 [[A:%.*]], i32 [[B:%.*]]) {
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; CHECK-NEXT: [[A_CMP:%.*]] = icmp ugt i32 [[A]], 32
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; CHECK-NEXT: br i1 [[A_CMP]], label [[END:%.*]], label [[L1:%.*]]
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; CHECK: l1:
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; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[B]], [[A]]
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; CHECK-NEXT: br i1 [[COND]], label [[L2:%.*]], label [[END]]
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; CHECK: l2:
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; CHECK-NEXT: call void @use(i1 true)
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; CHECK-NEXT: [[B_CMP2:%.*]] = icmp ult i32 [[B]], 31
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; CHECK-NEXT: call void @use(i1 [[B_CMP2]])
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; CHECK-NEXT: ret void
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; CHECK: end:
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; CHECK-NEXT: ret void
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;
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%a.cmp = icmp ugt i32 %a, 32
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br i1 %a.cmp, label %end, label %l1
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l1:
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%cond = icmp ult i32 %b, %a
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br i1 %cond, label %l2, label %end
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l2:
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%b.cmp1 = icmp ult i32 %b, 32
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call void @use(i1 %b.cmp1)
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%b.cmp2 = icmp ult i32 %b, 31
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call void @use(i1 %b.cmp2)
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ret void
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end:
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ret void
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}
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define i64 @test_sext_from_implied_cond(i32 %a, i32 %b) {
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; CHECK-LABEL: define i64 @test_sext_from_implied_cond(
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; CHECK-SAME: i32 [[A:%.*]], i32 [[B:%.*]]) {
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; CHECK-NEXT: [[A_CMP:%.*]] = icmp slt i32 [[A]], 0
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; CHECK-NEXT: br i1 [[A_CMP]], label [[END:%.*]], label [[L1:%.*]]
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; CHECK: l1:
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; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[B]], [[A]]
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; CHECK-NEXT: br i1 [[COND]], label [[L2:%.*]], label [[END]]
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; CHECK: l2:
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; CHECK-NEXT: [[SEXT:%.*]] = zext nneg i32 [[B]] to i64
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; CHECK-NEXT: ret i64 [[SEXT]]
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; CHECK: end:
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; CHECK-NEXT: ret i64 0
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;
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%a.cmp = icmp slt i32 %a, 0
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br i1 %a.cmp, label %end, label %l1
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l1:
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%cond = icmp ult i32 %b, %a
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br i1 %cond, label %l2, label %end
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l2:
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%sext = sext i32 %b to i64
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ret i64 %sext
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end:
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ret i64 0
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}
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define void @test_icmp_from_implied_range(i16 %x, i32 %b) {
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; CHECK-LABEL: define void @test_icmp_from_implied_range(
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; CHECK-SAME: i16 [[X:%.*]], i32 [[B:%.*]]) {
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; CHECK-NEXT: [[A:%.*]] = zext i16 [[X]] to i32
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; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[B]], [[A]]
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; CHECK-NEXT: br i1 [[COND]], label [[L1:%.*]], label [[END:%.*]]
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; CHECK: l1:
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; CHECK-NEXT: call void @use(i1 true)
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; CHECK-NEXT: [[B_CMP2:%.*]] = icmp ult i32 [[B]], 65534
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; CHECK-NEXT: call void @use(i1 [[B_CMP2]])
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; CHECK-NEXT: ret void
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; CHECK: end:
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; CHECK-NEXT: ret void
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;
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%a = zext i16 %x to i32
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%cond = icmp ult i32 %b, %a
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br i1 %cond, label %l1, label %end
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l1:
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%b.cmp1 = icmp ult i32 %b, 65535
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call void @use(i1 %b.cmp1)
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%b.cmp2 = icmp ult i32 %b, 65534
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call void @use(i1 %b.cmp2)
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ret void
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end:
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ret void
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}
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