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llvm-project/llvm/test/Transforms/IndVarSimplify/strengthen-overflow.ll

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This patch teaches IndVarSimplify to add nuw and nsw to certain kinds of operations that provably don't overflow. For example, we can prove %civ.inc below does not sign-overflow. With this change, IndVarSimplify changes %civ.inc to an add nsw. define i32 @foo(i32* %array, i32* %length_ptr, i32 %init) { entry: %length = load i32* %length_ptr, !range !0 %len.sub.1 = sub i32 %length, 1 %upper = icmp slt i32 %init, %len.sub.1 br i1 %upper, label %loop, label %exit loop: %civ = phi i32 [ %init, %entry ], [ %civ.inc, %latch ] %civ.inc = add i32 %civ, 1 %cmp = icmp slt i32 %civ.inc, %length br i1 %cmp, label %latch, label %break latch: store i32 0, i32* %array %check = icmp slt i32 %civ.inc, %len.sub.1 br i1 %check, label %loop, label %break break: ret i32 %civ.inc exit: ret i32 42 } Differential Revision: http://reviews.llvm.org/D6748 llvm-svn: 225282
2015-01-07 03:02:56 +08:00
; RUN: opt < %s -indvars -S | FileCheck %s
define i32 @test.signed.add.0(i32* %array, i32 %length, i32 %init) {
; CHECK-LABEL: @test.signed.add.0
entry:
%upper = icmp slt i32 %init, %length
br i1 %upper, label %loop, label %exit
loop:
; CHECK-LABEL: loop
%civ = phi i32 [ %init, %entry ], [ %civ.inc, %latch ]
%civ.inc = add i32 %civ, 1
; CHECK: %civ.inc = add nsw i32 %civ, 1
%cmp = icmp slt i32 %civ.inc, %length
br i1 %cmp, label %latch, label %break
latch:
store i32 0, i32* %array
%check = icmp slt i32 %civ.inc, %length
br i1 %check, label %loop, label %break
break:
ret i32 %civ.inc
exit:
ret i32 42
}
define i32 @test.signed.add.1(i32* %array, i32 %length, i32 %init) {
; CHECK-LABEL: @test.signed.add.1
entry:
%upper = icmp sle i32 %init, %length
br i1 %upper, label %loop, label %exit
loop:
; CHECK-LABEL: loop
%civ = phi i32 [ %init, %entry ], [ %civ.inc, %latch ]
%civ.inc = add i32 %civ, 1
; CHECK: %civ.inc = add i32 %civ, 1
%cmp = icmp slt i32 %civ.inc, %length
br i1 %cmp, label %latch, label %break
latch:
store i32 0, i32* %array
%check = icmp slt i32 %civ.inc, %length
br i1 %check, label %loop, label %break
break:
ret i32 %civ.inc
exit:
ret i32 42
}
define i32 @test.unsigned.add.0(i32* %array, i32 %length, i32 %init) {
; CHECK-LABEL: @test.unsigned.add.0
entry:
%upper = icmp ult i32 %init, %length
br i1 %upper, label %loop, label %exit
loop:
; CHECK-LABEL: loop
%civ = phi i32 [ %init, %entry ], [ %civ.inc, %latch ]
%civ.inc = add i32 %civ, 1
; CHECK: %civ.inc = add nuw i32 %civ, 1
%cmp = icmp slt i32 %civ.inc, %length
br i1 %cmp, label %latch, label %break
latch:
store i32 0, i32* %array
%check = icmp ult i32 %civ.inc, %length
br i1 %check, label %loop, label %break
break:
ret i32 %civ.inc
exit:
ret i32 42
}
define i32 @test.unsigned.add.1(i32* %array, i32 %length, i32 %init) {
; CHECK-LABEL: @test.unsigned.add.1
entry:
%upper = icmp ule i32 %init, %length
br i1 %upper, label %loop, label %exit
loop:
; CHECK-LABEL: loop
%civ = phi i32 [ %init, %entry ], [ %civ.inc, %latch ]
%civ.inc = add i32 %civ, 1
; CHECK: %civ.inc = add i32 %civ, 1
%cmp = icmp slt i32 %civ.inc, %length
br i1 %cmp, label %latch, label %break
latch:
store i32 0, i32* %array
%check = icmp ult i32 %civ.inc, %length
br i1 %check, label %loop, label %break
break:
ret i32 %civ.inc
exit:
ret i32 42
}
!0 = !{i32 0, i32 2}
!1 = !{i32 0, i32 42}