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llvm-6502/test/Transforms/IndVarSimplify/strengthen-overflow.ll
Sanjoy Das 31123d4529 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



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225282 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-06 19:02:56 +00:00

215 lines
4.9 KiB
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; 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.signed.sub.0(i32* %array, i32 %length, i32 %init) {
; CHECK-LABEL: @test.signed.sub.0
entry:
%upper = icmp sgt i32 %init, %length
br i1 %upper, label %loop, label %exit
loop:
; CHECK-LABEL: loop
%civ = phi i32 [ %init, %entry ], [ %civ.inc, %latch ]
%civ.inc = sub i32 %civ, 1
; CHECK: %civ.inc = sub 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 sgt i32 %civ.inc, %length
br i1 %check, label %loop, label %break
break:
ret i32 %civ.inc
exit:
ret i32 42
}
define i32 @test.signed.sub.1(i32* %array, i32 %length, i32 %init) {
; CHECK-LABEL: @test.signed.sub.1
entry:
%upper = icmp sgt i32 %init, %length
br i1 %upper, label %loop, label %exit
loop:
; CHECK-LABEL: loop
%civ = phi i32 [ %init, %entry ], [ %civ.inc, %latch ]
%civ.inc = sub i32 %civ, 1
; CHECK: %civ.inc = sub 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 sge 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
}
define i32 @test.unsigned.sub.0(i32* %array, i32* %length_ptr, i32 %init) {
; CHECK-LABEL: @test.unsigned.sub.0
entry:
%length = load i32* %length_ptr, !range !0
%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 = sub i32 %civ, 2
; CHECK: %civ.inc = sub nuw i32 %civ, 2
%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.sub.1(i32* %array, i32* %length_ptr, i32 %init) {
; CHECK-LABEL: @test.unsigned.sub.1
entry:
%length = load i32* %length_ptr, !range !1
%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 = sub i32 %civ, 2
; CHECK: %civ.inc = sub i32 %civ, 2
%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}
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