From dcc92918519125050edd5823567179143b20042a Mon Sep 17 00:00:00 2001 From: Jingyue Wu Date: Tue, 17 Jun 2014 00:42:07 +0000 Subject: [InstCombine] mark ADD with nuw if no unsigned overflow Summary: As a starting step, we only use one simple heuristic: if the sign bits of both a and b are zero, we can prove "add a, b" do not unsigned overflow, and thus convert it to "add nuw a, b". Updated all affected tests and added two new tests (@zero_sign_bit and @zero_sign_bit2) in AddOverflow.ll Test Plan: make check-all Reviewers: eliben, rafael, meheff, chandlerc Reviewed By: chandlerc Subscribers: chandlerc, llvm-commits Differential Revision: http://reviews.llvm.org/D4144 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211084 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/Transforms/InstCombine/AddOverFlow.ll | 24 +++++++++++++++++++++++- test/Transforms/InstCombine/add-sitofp.ll | 2 +- test/Transforms/InstCombine/ffs-1.ll | 6 +++--- test/Transforms/InstCombine/select.ll | 8 ++++---- 4 files changed, 31 insertions(+), 9 deletions(-) (limited to 'test') diff --git a/test/Transforms/InstCombine/AddOverFlow.ll b/test/Transforms/InstCombine/AddOverFlow.ll index 590c65af01..70178ec83b 100644 --- a/test/Transforms/InstCombine/AddOverFlow.ll +++ b/test/Transforms/InstCombine/AddOverFlow.ll @@ -12,6 +12,28 @@ define i16 @oppositesign(i16 %x, i16 %y) { ret i16 %c } +define i16 @zero_sign_bit(i16 %a) { +; CHECK-LABEL: @zero_sign_bit( +; CHECK-NEXT: and +; CHECK-NEXT: add nuw +; CHECK-NEXT: ret + %1 = and i16 %a, 32767 + %2 = add i16 %1, 512 + ret i16 %2 +} + +define i16 @zero_sign_bit2(i16 %a, i16 %b) { +; CHECK-LABEL: @zero_sign_bit2( +; CHECK-NEXT: and +; CHECK-NEXT: and +; CHECK-NEXT: add nuw +; CHECK-NEXT: ret + %1 = and i16 %a, 32767 + %2 = and i16 %b, 32767 + %3 = add i16 %1, %2 + ret i16 %3 +} + ; CHECK-LABEL: @ripple_nsw1 ; CHECK: add nsw i16 %a, %b define i16 @ripple_nsw1(i16 %x, i16 %y) { @@ -45,7 +67,7 @@ define i32 @ripple_no_nsw1(i32 %x, i32 %y) { } ; CHECK-LABEL: @ripple_no_nsw2 -; CHECK: add i16 %a, %b +; CHECK: add nuw i16 %a, %b define i16 @ripple_no_nsw2(i16 %x, i16 %y) { ; %a has at most one bit set %a = and i16 %y, 1 diff --git a/test/Transforms/InstCombine/add-sitofp.ll b/test/Transforms/InstCombine/add-sitofp.ll index 40edf7114a..3b5485e005 100644 --- a/test/Transforms/InstCombine/add-sitofp.ll +++ b/test/Transforms/InstCombine/add-sitofp.ll @@ -1,4 +1,4 @@ -; RUN: opt < %s -instcombine -S | grep "add nsw i32" +; RUN: opt < %s -instcombine -S | grep "add nuw nsw i32" define double @x(i32 %a, i32 %b) nounwind { %m = lshr i32 %a, 24 diff --git a/test/Transforms/InstCombine/ffs-1.ll b/test/Transforms/InstCombine/ffs-1.ll index 261f488613..c8763dc199 100644 --- a/test/Transforms/InstCombine/ffs-1.ll +++ b/test/Transforms/InstCombine/ffs-1.ll @@ -103,7 +103,7 @@ define i32 @test_simplify13(i32 %x) { ; CHECK-LABEL: @test_simplify13( %ret = call i32 @ffs(i32 %x) ; CHECK-NEXT: [[CTTZ:%[a-z0-9]+]] = call i32 @llvm.cttz.i32(i32 %x, i1 false) -; CHECK-NEXT: [[INC:%[a-z0-9]+]] = add nsw i32 [[CTTZ]], 1 +; CHECK-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i32 [[CTTZ]], 1 ; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i32 %x, 0 ; CHECK-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[CMP]], i32 [[INC]], i32 0 ret i32 %ret @@ -114,7 +114,7 @@ define i32 @test_simplify14(i32 %x) { ; CHECK-LINUX-LABEL: @test_simplify14( %ret = call i32 @ffsl(i32 %x) ; CHECK-LINUX-NEXT: [[CTTZ:%[a-z0-9]+]] = call i32 @llvm.cttz.i32(i32 %x, i1 false) -; CHECK-LINUX-NEXT: [[INC:%[a-z0-9]+]] = add nsw i32 [[CTTZ]], 1 +; CHECK-LINUX-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i32 [[CTTZ]], 1 ; CHECK-LINUX-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i32 %x, 0 ; CHECK-LINUX-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[CMP]], i32 [[INC]], i32 0 ret i32 %ret @@ -125,7 +125,7 @@ define i32 @test_simplify15(i64 %x) { ; CHECK-LINUX-LABEL: @test_simplify15( %ret = call i32 @ffsll(i64 %x) ; CHECK-LINUX-NEXT: [[CTTZ:%[a-z0-9]+]] = call i64 @llvm.cttz.i64(i64 %x, i1 false) -; CHECK-LINUX-NEXT: [[INC:%[a-z0-9]+]] = add nsw i64 [[CTTZ]], 1 +; CHECK-LINUX-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i64 [[CTTZ]], 1 ; CHECK-LINUX-NEXT: [[TRUNC:%[a-z0-9]+]] = trunc i64 [[INC]] to i32 ; CHECK-LINUX-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i64 %x, 0 ; CHECK-LINUX-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[CMP]], i32 [[TRUNC]], i32 0 diff --git a/test/Transforms/InstCombine/select.ll b/test/Transforms/InstCombine/select.ll index 762a9dad9f..d625f3b1b3 100644 --- a/test/Transforms/InstCombine/select.ll +++ b/test/Transforms/InstCombine/select.ll @@ -281,7 +281,7 @@ define i32 @test15i(i32 %X) { ; CHECK-NEXT: %t1 = shl i32 %X, 8 ; CHECK-NEXT: %1 = and i32 %t1, 512 ; CHECK-NEXT: %2 = xor i32 %1, 512 -; CHECK-NEXT: %3 = add nsw i32 %2, 577 +; CHECK-NEXT: %3 = add nuw nsw i32 %2, 577 ; CHECK-NEXT: ret i32 %3 } @@ -294,7 +294,7 @@ define i32 @test15j(i32 %X) { ; CHECK-LABEL: @test15j( ; CHECK-NEXT: %t1 = shl i32 %X, 8 ; CHECK-NEXT: %1 = and i32 %t1, 512 -; CHECK-NEXT: %2 = add nsw i32 %1, 577 +; CHECK-NEXT: %2 = add nuw nsw i32 %1, 577 ; CHECK-NEXT: ret i32 %2 } @@ -521,7 +521,7 @@ define i32 @test35(i32 %x) { ; CHECK-LABEL: @test35( ; CHECK: ashr i32 %x, 31 ; CHECK: and i32 {{.*}}, 40 -; CHECK: add nsw i32 {{.*}}, 60 +; CHECK: add nuw nsw i32 {{.*}}, 60 ; CHECK: ret } @@ -1235,4 +1235,4 @@ define i32 @test75(i32 %x) { ; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp ult i32 %x, 68 ; CHECK-NEXT: [[SEL:%[a-z0-9]+]] = select i1 [[CMP]], i32 68, i32 %x ; CHECK-NEXT: ret i32 [[SEL]] -} \ No newline at end of file +} -- cgit v1.2.3