llvm/test/Transforms/IndVarSimplify/overflow-intrinsics.ll
Sanjoy Das 59287c36a0 [IndVars] Eliminate op.with.overflow when possible (re-apply)
Summary:
If we can prove that an op.with.overflow intrinsic does not overflow, we
can get rid of the intrinsic, and replace it with non-wrapping
arithmetic.

This was first checked in at r265913 but reverted in r265950 because it
exposed some issues around how SCEV handled post-inc add recurrences.
Those issues have now been fixed.

Reviewers: atrick, regehr

Subscribers: sanjoy, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D18685

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271153 91177308-0d34-0410-b5e6-96231b3b80d8
2016-05-29 00:36:25 +00:00

138 lines
4.9 KiB
LLVM

; RUN: opt -S -indvars < %s | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define void @f_sadd(i8* %a) {
; CHECK-LABEL: @f_sadd(
entry:
br label %for.body
for.cond.cleanup: ; preds = %cont
ret void
for.body: ; preds = %entry, %cont
%i.04 = phi i32 [ 0, %entry ], [ %2, %cont ]
%idxprom = sext i32 %i.04 to i64
%arrayidx = getelementptr inbounds i8, i8* %a, i64 %idxprom
store i8 0, i8* %arrayidx, align 1
%0 = tail call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %i.04, i32 1)
%1 = extractvalue { i32, i1 } %0, 1
; CHECK: for.body:
; CHECK-NOT: @llvm.sadd.with.overflow
; CHECK: br i1 false, label %trap, label %cont, !nosanitize !0
br i1 %1, label %trap, label %cont, !nosanitize !{}
trap: ; preds = %for.body
tail call void @llvm.trap() #2, !nosanitize !{}
unreachable, !nosanitize !{}
cont: ; preds = %for.body
%2 = extractvalue { i32, i1 } %0, 0
%cmp = icmp slt i32 %2, 16
br i1 %cmp, label %for.body, label %for.cond.cleanup
}
define void @f_uadd(i8* %a) {
; CHECK-LABEL: @f_uadd(
entry:
br label %for.body
for.cond.cleanup: ; preds = %cont
ret void
for.body: ; preds = %entry, %cont
%i.04 = phi i32 [ 0, %entry ], [ %2, %cont ]
%idxprom = sext i32 %i.04 to i64
%arrayidx = getelementptr inbounds i8, i8* %a, i64 %idxprom
store i8 0, i8* %arrayidx, align 1
%0 = tail call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 %i.04, i32 1)
%1 = extractvalue { i32, i1 } %0, 1
; CHECK: for.body:
; CHECK-NOT: @llvm.uadd.with.overflow
; CHECK: br i1 false, label %trap, label %cont, !nosanitize !0
br i1 %1, label %trap, label %cont, !nosanitize !{}
trap: ; preds = %for.body
tail call void @llvm.trap(), !nosanitize !{}
unreachable, !nosanitize !{}
cont: ; preds = %for.body
%2 = extractvalue { i32, i1 } %0, 0
%cmp = icmp slt i32 %2, 16
br i1 %cmp, label %for.body, label %for.cond.cleanup
}
define void @f_ssub(i8* nocapture %a) {
; CHECK-LABEL: @f_ssub(
entry:
br label %for.body
for.cond.cleanup: ; preds = %cont
ret void
for.body: ; preds = %entry, %cont
%i.04 = phi i32 [ 15, %entry ], [ %2, %cont ]
%idxprom = sext i32 %i.04 to i64
%arrayidx = getelementptr inbounds i8, i8* %a, i64 %idxprom
store i8 0, i8* %arrayidx, align 1
%0 = tail call { i32, i1 } @llvm.ssub.with.overflow.i32(i32 %i.04, i32 1)
%1 = extractvalue { i32, i1 } %0, 1
; CHECK: for.body:
; CHECK-NOT: @llvm.ssub.with.overflow.i32
; CHECK: br i1 false, label %trap, label %cont, !nosanitize !0
br i1 %1, label %trap, label %cont, !nosanitize !{}
trap: ; preds = %for.body
tail call void @llvm.trap(), !nosanitize !{}
unreachable, !nosanitize !{}
cont: ; preds = %for.body
%2 = extractvalue { i32, i1 } %0, 0
%cmp = icmp sgt i32 %2, -1
br i1 %cmp, label %for.body, label %for.cond.cleanup
}
define void @f_usub(i8* nocapture %a) {
; CHECK-LABEL: @f_usub(
entry:
br label %for.body
for.cond.cleanup: ; preds = %cont
ret void
for.body: ; preds = %entry, %cont
%i.04 = phi i32 [ 15, %entry ], [ %2, %cont ]
%idxprom = sext i32 %i.04 to i64
%arrayidx = getelementptr inbounds i8, i8* %a, i64 %idxprom
store i8 0, i8* %arrayidx, align 1
%0 = tail call { i32, i1 } @llvm.usub.with.overflow.i32(i32 %i.04, i32 1)
%1 = extractvalue { i32, i1 } %0, 1
; It is theoretically possible to prove this, but SCEV cannot
; represent non-unsigned-wrapping subtraction operations.
; CHECK: for.body:
; CHECK: [[COND:%[^ ]+]] = extractvalue { i32, i1 } %1, 1
; CHECK-NEXT: br i1 [[COND]], label %trap, label %cont, !nosanitize !0
br i1 %1, label %trap, label %cont, !nosanitize !{}
trap: ; preds = %for.body
tail call void @llvm.trap(), !nosanitize !{}
unreachable, !nosanitize !{}
cont: ; preds = %for.body
%2 = extractvalue { i32, i1 } %0, 0
%cmp = icmp sgt i32 %2, -1
br i1 %cmp, label %for.body, label %for.cond.cleanup
}
declare { i32, i1 } @llvm.sadd.with.overflow.i32(i32, i32) nounwind readnone
declare { i32, i1 } @llvm.uadd.with.overflow.i32(i32, i32) nounwind readnone
declare { i32, i1 } @llvm.ssub.with.overflow.i32(i32, i32) nounwind readnone
declare { i32, i1 } @llvm.usub.with.overflow.i32(i32, i32) nounwind readnone
declare { i32, i1 } @llvm.smul.with.overflow.i32(i32, i32) nounwind readnone
declare { i32, i1 } @llvm.umul.with.overflow.i32(i32, i32) nounwind readnone
declare void @llvm.trap() #2