diff options
Diffstat (limited to 'llvm/test/Transforms/InstCombine/abs-1.ll')
| -rw-r--r-- | llvm/test/Transforms/InstCombine/abs-1.ll | 571 |
1 files changed, 571 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/abs-1.ll b/llvm/test/Transforms/InstCombine/abs-1.ll new file mode 100644 index 00000000000..8bbc833d5d4 --- /dev/null +++ b/llvm/test/Transforms/InstCombine/abs-1.ll @@ -0,0 +1,571 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; RUN: opt < %s -instcombine -S | FileCheck %s + +target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128" + +declare i32 @abs(i32) +declare i64 @labs(i64) +declare i64 @llabs(i64) + +; Test that the abs library call simplifier works correctly. +; abs(x) -> x <s 0 ? -x : x. + +define i32 @test_abs(i32 %x) { +; CHECK-LABEL: @test_abs( +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub nsw i32 0, [[X]] +; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 [[NEG]], i32 [[X]] +; CHECK-NEXT: ret i32 [[TMP2]] +; + %ret = call i32 @abs(i32 %x) + ret i32 %ret +} + +define i64 @test_labs(i64 %x) { +; CHECK-LABEL: @test_labs( +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i64 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub nsw i64 0, [[X]] +; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i64 [[NEG]], i64 [[X]] +; CHECK-NEXT: ret i64 [[TMP2]] +; + %ret = call i64 @labs(i64 %x) + ret i64 %ret +} + +define i64 @test_llabs(i64 %x) { +; CHECK-LABEL: @test_llabs( +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i64 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub nsw i64 0, [[X]] +; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i64 [[NEG]], i64 [[X]] +; CHECK-NEXT: ret i64 [[TMP2]] +; + %ret = call i64 @llabs(i64 %x) + ret i64 %ret +} + +; We have a canonical form of abs to make CSE easier. + +define i8 @abs_canonical_1(i8 %x) { +; CHECK-LABEL: @abs_canonical_1( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub i8 0, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i8 [[NEG]], i8 [[X]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %cmp = icmp sgt i8 %x, 0 + %neg = sub i8 0, %x + %abs = select i1 %cmp, i8 %x, i8 %neg + ret i8 %abs +} + +; Vectors should work too. + +define <2 x i8> @abs_canonical_2(<2 x i8> %x) { +; CHECK-LABEL: @abs_canonical_2( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer +; CHECK-NEXT: [[NEG:%.*]] = sub <2 x i8> zeroinitializer, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[NEG]], <2 x i8> [[X]] +; CHECK-NEXT: ret <2 x i8> [[ABS]] +; + %cmp = icmp sgt <2 x i8> %x, <i8 -1, i8 -1> + %neg = sub <2 x i8> zeroinitializer, %x + %abs = select <2 x i1> %cmp, <2 x i8> %x, <2 x i8> %neg + ret <2 x i8> %abs +} + +; Even if a constant has undef elements. + +define <2 x i8> @abs_canonical_2_vec_undef_elts(<2 x i8> %x) { +; CHECK-LABEL: @abs_canonical_2_vec_undef_elts( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer +; CHECK-NEXT: [[NEG:%.*]] = sub <2 x i8> zeroinitializer, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[NEG]], <2 x i8> [[X]] +; CHECK-NEXT: ret <2 x i8> [[ABS]] +; + %cmp = icmp sgt <2 x i8> %x, <i8 undef, i8 -1> + %neg = sub <2 x i8> zeroinitializer, %x + %abs = select <2 x i1> %cmp, <2 x i8> %x, <2 x i8> %neg + ret <2 x i8> %abs +} + +; NSW should not change. + +define i8 @abs_canonical_3(i8 %x) { +; CHECK-LABEL: @abs_canonical_3( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub nsw i8 0, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i8 [[NEG]], i8 [[X]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %cmp = icmp slt i8 %x, 0 + %neg = sub nsw i8 0, %x + %abs = select i1 %cmp, i8 %neg, i8 %x + ret i8 %abs +} + +define i8 @abs_canonical_4(i8 %x) { +; CHECK-LABEL: @abs_canonical_4( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub i8 0, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i8 [[NEG]], i8 [[X]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %cmp = icmp slt i8 %x, 1 + %neg = sub i8 0, %x + %abs = select i1 %cmp, i8 %neg, i8 %x + ret i8 %abs +} + +define i32 @abs_canonical_5(i8 %x) { +; CHECK-LABEL: @abs_canonical_5( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[CONV:%.*]] = sext i8 [[X]] to i32 +; CHECK-NEXT: [[NEG:%.*]] = sub nsw i32 0, [[CONV]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[NEG]], i32 [[CONV]] +; CHECK-NEXT: ret i32 [[ABS]] +; + %cmp = icmp sgt i8 %x, 0 + %conv = sext i8 %x to i32 + %neg = sub i32 0, %conv + %abs = select i1 %cmp, i32 %conv, i32 %neg + ret i32 %abs +} + +define i32 @abs_canonical_6(i32 %a, i32 %b) { +; CHECK-LABEL: @abs_canonical_6( +; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP1]], 0 +; CHECK-NEXT: [[TMP2:%.*]] = sub i32 0, [[TMP1]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP2]], i32 [[TMP1]] +; CHECK-NEXT: ret i32 [[ABS]] +; + %tmp1 = sub i32 %a, %b + %cmp = icmp sgt i32 %tmp1, -1 + %tmp2 = sub i32 %b, %a + %abs = select i1 %cmp, i32 %tmp1, i32 %tmp2 + ret i32 %abs +} + +define <2 x i8> @abs_canonical_7(<2 x i8> %a, <2 x i8 > %b) { +; CHECK-LABEL: @abs_canonical_7( +; CHECK-NEXT: [[TMP1:%.*]] = sub <2 x i8> [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt <2 x i8> [[TMP1]], zeroinitializer +; CHECK-NEXT: [[TMP2:%.*]] = sub <2 x i8> zeroinitializer, [[TMP1]] +; CHECK-NEXT: [[ABS:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[TMP2]], <2 x i8> [[TMP1]] +; CHECK-NEXT: ret <2 x i8> [[ABS]] +; + + %tmp1 = sub <2 x i8> %a, %b + %cmp = icmp sgt <2 x i8> %tmp1, <i8 -1, i8 -1> + %tmp2 = sub <2 x i8> %b, %a + %abs = select <2 x i1> %cmp, <2 x i8> %tmp1, <2 x i8> %tmp2 + ret <2 x i8> %abs +} + +define i32 @abs_canonical_8(i32 %a) { +; CHECK-LABEL: @abs_canonical_8( +; CHECK-NEXT: [[TMP:%.*]] = sub i32 0, [[A:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[A]], 0 +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP]], i32 [[A]] +; CHECK-NEXT: ret i32 [[ABS]] +; + %tmp = sub i32 0, %a + %cmp = icmp slt i32 %tmp, 0 + %abs = select i1 %cmp, i32 %a, i32 %tmp + ret i32 %abs +} + +define i32 @abs_canonical_9(i32 %a, i32 %b) { +; CHECK-LABEL: @abs_canonical_9( +; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[TMP1]], -1 +; CHECK-NEXT: [[TMP2:%.*]] = sub i32 [[B]], [[A]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP1]], i32 [[TMP2]] +; CHECK-NEXT: [[ADD:%.*]] = add i32 [[ABS]], [[TMP2]] +; CHECK-NEXT: ret i32 [[ADD]] +; + %tmp1 = sub i32 %a, %b + %cmp = icmp sgt i32 %tmp1, -1 + %tmp2 = sub i32 %b, %a + %abs = select i1 %cmp, i32 %tmp1, i32 %tmp2 + %add = add i32 %abs, %tmp2 ; increase use count for %tmp2. + ret i32 %add +} + +define i32 @abs_canonical_10(i32 %a, i32 %b) { +; CHECK-LABEL: @abs_canonical_10( +; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP1]], 0 +; CHECK-NEXT: [[NEGTMP:%.*]] = sub i32 0, [[TMP1]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[NEGTMP]], i32 [[TMP1]] +; CHECK-NEXT: ret i32 [[ABS]] +; + %tmp2 = sub i32 %b, %a + %tmp1 = sub i32 %a, %b + %cmp = icmp sgt i32 %tmp1, -1 + %abs = select i1 %cmp, i32 %tmp1, i32 %tmp2 + ret i32 %abs +} + +; We have a canonical form of nabs to make CSE easier. + +define i8 @nabs_canonical_1(i8 %x) { +; CHECK-LABEL: @nabs_canonical_1( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub i8 0, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i8 [[X]], i8 [[NEG]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %cmp = icmp sgt i8 %x, 0 + %neg = sub i8 0, %x + %abs = select i1 %cmp, i8 %neg, i8 %x + ret i8 %abs +} + +; Vectors should work too. + +define <2 x i8> @nabs_canonical_2(<2 x i8> %x) { +; CHECK-LABEL: @nabs_canonical_2( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer +; CHECK-NEXT: [[NEG:%.*]] = sub <2 x i8> zeroinitializer, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[X]], <2 x i8> [[NEG]] +; CHECK-NEXT: ret <2 x i8> [[ABS]] +; + %cmp = icmp sgt <2 x i8> %x, <i8 -1, i8 -1> + %neg = sub <2 x i8> zeroinitializer, %x + %abs = select <2 x i1> %cmp, <2 x i8> %neg, <2 x i8> %x + ret <2 x i8> %abs +} + +; Even if a constant has undef elements. + +define <2 x i8> @nabs_canonical_2_vec_undef_elts(<2 x i8> %x) { +; CHECK-LABEL: @nabs_canonical_2_vec_undef_elts( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer +; CHECK-NEXT: [[NEG:%.*]] = sub <2 x i8> zeroinitializer, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[X]], <2 x i8> [[NEG]] +; CHECK-NEXT: ret <2 x i8> [[ABS]] +; + %cmp = icmp sgt <2 x i8> %x, <i8 -1, i8 undef> + %neg = sub <2 x i8> zeroinitializer, %x + %abs = select <2 x i1> %cmp, <2 x i8> %neg, <2 x i8> %x + ret <2 x i8> %abs +} + +; NSW should not change. + +define i8 @nabs_canonical_3(i8 %x) { +; CHECK-LABEL: @nabs_canonical_3( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub nsw i8 0, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i8 [[X]], i8 [[NEG]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %cmp = icmp slt i8 %x, 0 + %neg = sub nsw i8 0, %x + %abs = select i1 %cmp, i8 %x, i8 %neg + ret i8 %abs +} + +define i8 @nabs_canonical_4(i8 %x) { +; CHECK-LABEL: @nabs_canonical_4( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[NEG:%.*]] = sub i8 0, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i8 [[X]], i8 [[NEG]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %cmp = icmp slt i8 %x, 1 + %neg = sub i8 0, %x + %abs = select i1 %cmp, i8 %x, i8 %neg + ret i8 %abs +} + +define i32 @nabs_canonical_5(i8 %x) { +; CHECK-LABEL: @nabs_canonical_5( +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[CONV:%.*]] = sext i8 [[X]] to i32 +; CHECK-NEXT: [[NEG:%.*]] = sub nsw i32 0, [[CONV]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[CONV]], i32 [[NEG]] +; CHECK-NEXT: ret i32 [[ABS]] +; + %cmp = icmp sgt i8 %x, 0 + %conv = sext i8 %x to i32 + %neg = sub i32 0, %conv + %abs = select i1 %cmp, i32 %neg, i32 %conv + ret i32 %abs +} + +define i32 @nabs_canonical_6(i32 %a, i32 %b) { +; CHECK-LABEL: @nabs_canonical_6( +; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP1]], 0 +; CHECK-NEXT: [[TMP2:%.*]] = sub i32 0, [[TMP1]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP1]], i32 [[TMP2]] +; CHECK-NEXT: ret i32 [[ABS]] +; + %tmp1 = sub i32 %a, %b + %cmp = icmp sgt i32 %tmp1, -1 + %tmp2 = sub i32 %b, %a + %abs = select i1 %cmp, i32 %tmp2, i32 %tmp1 + ret i32 %abs +} + +define <2 x i8> @nabs_canonical_7(<2 x i8> %a, <2 x i8 > %b) { +; CHECK-LABEL: @nabs_canonical_7( +; CHECK-NEXT: [[TMP1:%.*]] = sub <2 x i8> [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt <2 x i8> [[TMP1]], zeroinitializer +; CHECK-NEXT: [[TMP2:%.*]] = sub <2 x i8> zeroinitializer, [[TMP1]] +; CHECK-NEXT: [[ABS:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[TMP1]], <2 x i8> [[TMP2]] +; CHECK-NEXT: ret <2 x i8> [[ABS]] +; + %tmp1 = sub <2 x i8> %a, %b + %cmp = icmp sgt <2 x i8> %tmp1, <i8 -1, i8 -1> + %tmp2 = sub <2 x i8> %b, %a + %abs = select <2 x i1> %cmp, <2 x i8> %tmp2, <2 x i8> %tmp1 + ret <2 x i8> %abs +} + +define i32 @nabs_canonical_8(i32 %a) { +; CHECK-LABEL: @nabs_canonical_8( +; CHECK-NEXT: [[TMP:%.*]] = sub i32 0, [[A:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[A]], 0 +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[A]], i32 [[TMP]] +; CHECK-NEXT: ret i32 [[ABS]] +; + %tmp = sub i32 0, %a + %cmp = icmp slt i32 %tmp, 0 + %abs = select i1 %cmp, i32 %tmp, i32 %a + ret i32 %abs +} + +define i32 @nabs_canonical_9(i32 %a, i32 %b) { +; CHECK-LABEL: @nabs_canonical_9( +; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[TMP1]], -1 +; CHECK-NEXT: [[TMP2:%.*]] = sub i32 [[B]], [[A]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP2]], i32 [[TMP1]] +; CHECK-NEXT: [[ADD:%.*]] = add i32 [[TMP2]], [[ABS]] +; CHECK-NEXT: ret i32 [[ADD]] +; + %tmp1 = sub i32 %a, %b + %cmp = icmp sgt i32 %tmp1, -1 + %tmp2 = sub i32 %b, %a + %abs = select i1 %cmp, i32 %tmp2, i32 %tmp1 + %add = add i32 %tmp2, %abs ; increase use count for %tmp2 + ret i32 %add +} + +define i32 @nabs_canonical_10(i32 %a, i32 %b) { +; CHECK-LABEL: @nabs_canonical_10( +; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP1]], 0 +; CHECK-NEXT: [[NEGTMP:%.*]] = sub i32 0, [[TMP1]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[TMP1]], i32 [[NEGTMP]] +; CHECK-NEXT: ret i32 [[ABS]] +; + %tmp2 = sub i32 %b, %a + %tmp1 = sub i32 %a, %b + %cmp = icmp slt i32 %tmp1, 1 + %abs = select i1 %cmp, i32 %tmp1, i32 %tmp2 + ret i32 %abs +} + +; The following 5 tests use a shift+add+xor to implement abs(): +; B = ashr i8 A, 7 -- smear the sign bit. +; xor (add A, B), B -- add -1 and flip bits if negative + +define i8 @shifty_abs_commute0(i8 %x) { +; CHECK-LABEL: @shifty_abs_commute0( +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[TMP2:%.*]] = sub i8 0, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[TMP1]], i8 [[TMP2]], i8 [[X]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %signbit = ashr i8 %x, 7 + %add = add i8 %signbit, %x + %abs = xor i8 %add, %signbit + ret i8 %abs +} + +define i8 @shifty_abs_commute0_nsw(i8 %x) { +; CHECK-LABEL: @shifty_abs_commute0_nsw( +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[TMP2:%.*]] = sub nsw i8 0, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[TMP1]], i8 [[TMP2]], i8 [[X]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %signbit = ashr i8 %x, 7 + %add = add nsw i8 %signbit, %x + %abs = xor i8 %add, %signbit + ret i8 %abs +} + +; The nuw flag creates a contradiction. If the shift produces all 1s, the only +; way for the add to not wrap is for %x to be 0, but then the shift couldn't +; have produced all 1s. We partially optimize this. +define i8 @shifty_abs_commute0_nuw(i8 %x) { +; CHECK-LABEL: @shifty_abs_commute0_nuw( +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[TMP1]], i8 [[X]], i8 0 +; CHECK-NEXT: ret i8 [[ABS]] +; + %signbit = ashr i8 %x, 7 + %add = add nuw i8 %signbit, %x + %abs = xor i8 %add, %signbit + ret i8 %abs +} + +define <2 x i8> @shifty_abs_commute1(<2 x i8> %x) { +; CHECK-LABEL: @shifty_abs_commute1( +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer +; CHECK-NEXT: [[TMP2:%.*]] = sub <2 x i8> zeroinitializer, [[X]] +; CHECK-NEXT: [[ABS:%.*]] = select <2 x i1> [[TMP1]], <2 x i8> [[TMP2]], <2 x i8> [[X]] +; CHECK-NEXT: ret <2 x i8> [[ABS]] +; + %signbit = ashr <2 x i8> %x, <i8 7, i8 7> + %add = add <2 x i8> %signbit, %x + %abs = xor <2 x i8> %signbit, %add + ret <2 x i8> %abs +} + +define <2 x i8> @shifty_abs_commute2(<2 x i8> %x) { +; CHECK-LABEL: @shifty_abs_commute2( +; CHECK-NEXT: [[Y:%.*]] = mul <2 x i8> [[X:%.*]], <i8 3, i8 3> +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt <2 x i8> [[Y]], zeroinitializer +; CHECK-NEXT: [[TMP2:%.*]] = sub <2 x i8> zeroinitializer, [[Y]] +; CHECK-NEXT: [[ABS:%.*]] = select <2 x i1> [[TMP1]], <2 x i8> [[TMP2]], <2 x i8> [[Y]] +; CHECK-NEXT: ret <2 x i8> [[ABS]] +; + %y = mul <2 x i8> %x, <i8 3, i8 3> ; extra op to thwart complexity-based canonicalization + %signbit = ashr <2 x i8> %y, <i8 7, i8 7> + %add = add <2 x i8> %y, %signbit + %abs = xor <2 x i8> %signbit, %add + ret <2 x i8> %abs +} + +define i8 @shifty_abs_commute3(i8 %x) { +; CHECK-LABEL: @shifty_abs_commute3( +; CHECK-NEXT: [[Y:%.*]] = mul i8 [[X:%.*]], 3 +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i8 [[Y]], 0 +; CHECK-NEXT: [[TMP2:%.*]] = sub i8 0, [[Y]] +; CHECK-NEXT: [[ABS:%.*]] = select i1 [[TMP1]], i8 [[TMP2]], i8 [[Y]] +; CHECK-NEXT: ret i8 [[ABS]] +; + %y = mul i8 %x, 3 ; extra op to thwart complexity-based canonicalization + %signbit = ashr i8 %y, 7 + %add = add i8 %y, %signbit + %abs = xor i8 %add, %signbit + ret i8 %abs +} + +; Negative test - don't transform if it would increase instruction count. + +declare void @extra_use(i8) + +define i8 @shifty_abs_too_many_uses(i8 %x) { +; CHECK-LABEL: @shifty_abs_too_many_uses( +; CHECK-NEXT: [[SIGNBIT:%.*]] = ashr i8 [[X:%.*]], 7 +; CHECK-NEXT: [[ADD:%.*]] = add i8 [[SIGNBIT]], [[X]] +; CHECK-NEXT: [[ABS:%.*]] = xor i8 [[ADD]], [[SIGNBIT]] +; CHECK-NEXT: call void @extra_use(i8 [[SIGNBIT]]) +; CHECK-NEXT: ret i8 [[ABS]] +; + %signbit = ashr i8 %x, 7 + %add = add i8 %x, %signbit + %abs = xor i8 %add, %signbit + call void @extra_use(i8 %signbit) + ret i8 %abs +} + +; There's another way to make abs() using shift, xor, and subtract. +; PR36036 - https://bugs.llvm.org/show_bug.cgi?id=36036 + +define i8 @shifty_sub(i8 %x) { +; CHECK-LABEL: @shifty_sub( +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[TMP2:%.*]] = sub i8 0, [[X]] +; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i8 [[TMP2]], i8 [[X]] +; CHECK-NEXT: ret i8 [[R]] +; + %sh = ashr i8 %x, 7 + %xor = xor i8 %x, %sh + %r = sub i8 %xor, %sh + ret i8 %r +} + +define i8 @shifty_sub_nsw_commute(i8 %x) { +; CHECK-LABEL: @shifty_sub_nsw_commute( +; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i8 [[X:%.*]], 0 +; CHECK-NEXT: [[TMP2:%.*]] = sub nsw i8 0, [[X]] +; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i8 [[TMP2]], i8 [[X]] +; CHECK-NEXT: ret i8 [[R]] +; + %sh = ashr i8 %x, 7 + %xor = xor i8 %sh, %x + %r = sub nsw i8 %xor, %sh + ret i8 %r +} + +define <4 x i32> @shifty_sub_nuw_vec_commute(<4 x i32> %x) { +; CHECK-LABEL: @shifty_sub_nuw_vec_commute( +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt <4 x i32> [[X:%.*]], zeroinitializer +; CHECK-NEXT: [[R:%.*]] = select <4 x i1> [[TMP1]], <4 x i32> [[X]], <4 x i32> zeroinitializer +; CHECK-NEXT: ret <4 x i32> [[R]] +; + %sh = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31> + %xor = xor <4 x i32> %sh, %x + %r = sub nuw <4 x i32> %xor, %sh + ret <4 x i32> %r +} + +define i12 @shifty_sub_nsw_nuw(i12 %x) { +; CHECK-LABEL: @shifty_sub_nsw_nuw( +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i12 [[X:%.*]], 0 +; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i12 [[X]], i12 0 +; CHECK-NEXT: ret i12 [[R]] +; + %sh = ashr i12 %x, 11 + %xor = xor i12 %x, %sh + %r = sub nsw nuw i12 %xor, %sh + ret i12 %r +} + +define i8 @negate_abs(i8 %x) { +; CHECK-LABEL: @negate_abs( +; CHECK-NEXT: [[N:%.*]] = sub i8 0, [[X:%.*]] +; CHECK-NEXT: [[C:%.*]] = icmp slt i8 [[X]], 0 +; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i8 [[X]], i8 [[N]] +; CHECK-NEXT: ret i8 [[S]] +; + %n = sub i8 0, %x + %c = icmp slt i8 %x, 0 + %s = select i1 %c, i8 %n, i8 %x + %r = sub i8 0, %s + ret i8 %r +} + +define <2 x i8> @negate_nabs(<2 x i8> %x) { +; CHECK-LABEL: @negate_nabs( +; CHECK-NEXT: [[N:%.*]] = sub <2 x i8> zeroinitializer, [[X:%.*]] +; CHECK-NEXT: [[C:%.*]] = icmp slt <2 x i8> [[X]], zeroinitializer +; CHECK-NEXT: [[S:%.*]] = select <2 x i1> [[C]], <2 x i8> [[N]], <2 x i8> [[X]] +; CHECK-NEXT: ret <2 x i8> [[S]] +; + %n = sub <2 x i8> zeroinitializer, %x + %c = icmp slt <2 x i8> %x, zeroinitializer + %s = select <2 x i1> %c, <2 x i8> %x, <2 x i8> %n + %r = sub <2 x i8> zeroinitializer, %s + ret <2 x i8> %r +} + +define i1 @abs_must_be_positive(i32 %x) { +; CHECK-LABEL: @abs_must_be_positive( +; CHECK-NEXT: ret i1 true +; + %negx = sub nsw i32 0, %x + %c = icmp sge i32 %x, 0 + %sel = select i1 %c, i32 %x, i32 %negx + %c2 = icmp sge i32 %sel, 0 + ret i1 %c2 +} + |
