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llvm-mirror/test/Transforms/NewGVN/compare-condition-changes.ll
Florian Hahn 2aa8af916f [NewGVN] Use performSymbolicEvaluation instead of createExpression.
performSymbolicEvaluation is used to obtain the symbolic expression when
visiting instructions and this is used to determine their congruence
class.

performSymbolicEvaluation only creates expressions for certain
instructions (via createExpression). For unsupported instructions,
'unknown' expression are created.

The use of createExpression in processOutgoingEdges means we may
simplify the condition in processOutgoingEdges to a constant in the
initial round of processing, but we use Unknown(I) for the congruence
class. If an operand of I changes the expression Unknown(I) stays the
same, so there is no update of the congruence class of I. Hence it
won't get re-visited. So if an operand of I changes in a way that causes
createExpression to return different result, this update is missed.

This patch updates the code to use performSymbolicEvaluation, to be
symmetric with the congruence class updating code.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D99990
2021-04-24 18:49:07 +01:00

81 lines
2.4 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -newgvn -S %s | FileCheck %s
; Test cases to make sure the blocks are properly marked as executable, if the
; state of the branch condition changes.
; Test case to make sure the case where a condition cannot be simplified is
; handled properly.
define i1 @test1() {
; CHECK-LABEL: @test1(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CALL:%.*]] = tail call i1 @foo()
; CHECK-NEXT: br i1 [[CALL]], label [[THEN:%.*]], label [[ELSE:%.*]]
; CHECK: then:
; CHECK-NEXT: ret i1 true
; CHECK: else:
; CHECK-NEXT: ret i1 false
;
entry:
%call = tail call i1 @foo()
br i1 %call, label %then, label %else
then:
ret i1 true
else:
ret i1 false
}
declare i1 @foo()
; Make sure state changes are propagated across freeze to branches.
define void @test2(i1 %c) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
; CHECK: loop.header:
; CHECK-NEXT: [[P_0:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[LOOP_LATCH:%.*]] ]
; CHECK-NEXT: [[P_1:%.*]] = phi i32 [ 1, [[ENTRY]] ], [ [[P_2:%.*]], [[LOOP_LATCH]] ]
; CHECK-NEXT: br label [[LOOP_BB_1:%.*]]
; CHECK: loop.bb.1:
; CHECK-NEXT: [[INC]] = add nsw i32 [[P_0]], 1
; CHECK-NEXT: [[C_1:%.*]] = icmp slt i32 [[P_0]], 0
; CHECK-NEXT: [[C_1_FREEZE:%.*]] = freeze i1 [[C_1]]
; CHECK-NEXT: br i1 [[C_1_FREEZE]], label [[LOOP_BB_2:%.*]], label [[LOOP_LATCH]]
; CHECK: loop.bb.2:
; CHECK-NEXT: br label [[LOOP_LATCH]]
; CHECK: loop.latch:
; CHECK-NEXT: [[P_2]] = phi i32 [ 0, [[LOOP_BB_2]] ], [ [[P_1]], [[LOOP_BB_1]] ]
; CHECK-NEXT: [[C_2:%.*]] = icmp eq i32 [[P_2]], 123
; CHECK-NEXT: br i1 [[C_2]], label [[EXIT:%.*]], label [[LOOP_HEADER]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
br label %loop.header
loop.header:
%p.0 = phi i32 [ 0, %entry ], [ %p.3, %loop.latch ]
%p.1 = phi i32 [ 1, %entry ], [ %p.2, %loop.latch ]
br label %loop.bb.1
loop.bb.1:
%inc = add nsw i32 %p.0, 1
%c.1 = icmp slt i32 %p.0, 0
%c.1.freeze = freeze i1 %c.1
br i1 %c.1.freeze, label %loop.bb.2, label %loop.latch
loop.bb.2:
br label %loop.latch
loop.latch:
%p.2 = phi i32 [ 0, %loop.bb.2 ], [ %p.1, %loop.bb.1 ]
%p.3 = phi i32 [ %inc, %loop.bb.2 ], [ %inc, %loop.bb.1 ]
%c.2 = icmp eq i32 %p.2, 123
br i1 %c.2, label %exit, label %loop.header
exit:
ret void
}