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generalize the sadd creation code to not require that the

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sadd formed is half the size of the original type. We can
now compile this into a sadd.i8:

unsigned char X(char a, char b) {
  int res = a+b;
  if ((unsigned )(res+128) > 255U)
    abort();
  return res;
}




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122178 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2010-12-19 18:35:09 +00:00
parent dd7e837374
commit 0a62474830
2 changed files with 43 additions and 43 deletions
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31
test/Transforms/InstCombine/overflow.ll
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@ -1,7 +1,7 @@
; RUN: opt -S -instcombine < %s | FileCheck %s
; <rdar://problem/8558713>
declare i32 @throwAnExceptionOrWhatever(...)
declare void @throwAnExceptionOrWhatever()
; CHECK: @test1
define i32 @test1(i32 %a, i32 %b) nounwind ssp {
@ -16,7 +16,7 @@ entry:
br i1 %0, label %if.then, label %if.end
if.then:
%call = tail call i32 (...)* @throwAnExceptionOrWhatever() nounwind
tail call void @throwAnExceptionOrWhatever() nounwind
br label %if.end
if.end:
@ -44,7 +44,7 @@ entry:
br i1 %0, label %if.then, label %if.end
if.then:
%call = tail call i32 (...)* @throwAnExceptionOrWhatever() nounwind
tail call void @throwAnExceptionOrWhatever() nounwind
br label %if.end
if.end:
@ -54,6 +54,7 @@ if.end:
}
; CHECK: test3
; PR8816
; This is illegal to transform because the high bits of the original add are
; live out.
define i64 @test3(i32 %a, i32 %b) nounwind ssp {
@ -67,10 +68,32 @@ entry:
br i1 %0, label %if.then, label %if.end
if.then:
%call = tail call i32 (...)* @throwAnExceptionOrWhatever() nounwind
tail call void @throwAnExceptionOrWhatever() nounwind
br label %if.end
if.end:
ret i64 %add
; CHECK: ret i64
}
; CHECK: @test4
; Should be able to form an i8 sadd computed in an i32.
define zeroext i8 @test4(i8 signext %a, i8 signext %b) nounwind ssp {
entry:
%conv = sext i8 %a to i32
%conv2 = sext i8 %b to i32
%add = add nsw i32 %conv2, %conv
%add4 = add nsw i32 %add, 128
%cmp = icmp ugt i32 %add4, 255
br i1 %cmp, label %if.then, label %if.end
; CHECK: llvm.sadd.with.overflow.i8
if.then: ; preds = %entry
tail call void @throwAnExceptionOrWhatever() nounwind
unreachable
if.end: ; preds = %entry
%conv7 = trunc i32 %add to i8
ret i8 %conv7
; CHECK: ret i8
}