summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--llvm/lib/Analysis/InstructionSimplify.cpp7
-rw-r--r--llvm/test/Transforms/InstCombine/set-lowbits-mask-canonicalize.ll32
-rw-r--r--llvm/test/Transforms/InstSimplify/constantfold-shl-nuw-C-to-C.ll18
3 files changed, 21 insertions, 36 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index cdcb81b8060..0b150f86a32 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -1226,6 +1226,13 @@ static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
Value *X;
if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
return X;
+
+ // shl nuw i8 C, %x -> C iff C has sign bit set.
+ if (isNUW && match(Op0, m_Negative()))
+ return Op0;
+ // NOTE: could use computeKnownBits() / LazyValueInfo,
+ // but the cost-benefit analysis suggests it isn't worth it.
+
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/set-lowbits-mask-canonicalize.ll b/llvm/test/Transforms/InstCombine/set-lowbits-mask-canonicalize.ll
index e5afb8e5554..b67854c34ed 100644
--- a/llvm/test/Transforms/InstCombine/set-lowbits-mask-canonicalize.ll
+++ b/llvm/test/Transforms/InstCombine/set-lowbits-mask-canonicalize.ll
@@ -39,9 +39,7 @@ define i32 @shl_add_nsw(i32 %NBits) {
define i32 @shl_add_nuw(i32 %NBits) {
; CHECK-LABEL: @shl_add_nuw(
-; CHECK-NEXT: [[NOTMASK:%.*]] = shl nuw nsw i32 -1, [[NBITS:%.*]]
-; CHECK-NEXT: [[RET:%.*]] = xor i32 [[NOTMASK]], -1
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 0
;
%setbit = shl i32 1, %NBits
%ret = add nuw i32 %setbit, -1
@@ -50,9 +48,7 @@ define i32 @shl_add_nuw(i32 %NBits) {
define i32 @shl_add_nsw_nuw(i32 %NBits) {
; CHECK-LABEL: @shl_add_nsw_nuw(
-; CHECK-NEXT: [[NOTMASK:%.*]] = shl nuw nsw i32 -1, [[NBITS:%.*]]
-; CHECK-NEXT: [[RET:%.*]] = xor i32 [[NOTMASK]], -1
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 0
;
%setbit = shl i32 1, %NBits
%ret = add nuw nsw i32 %setbit, -1
@@ -85,9 +81,7 @@ define i32 @shl_nsw_add_nsw(i32 %NBits) {
define i32 @shl_nsw_add_nuw(i32 %NBits) {
; CHECK-LABEL: @shl_nsw_add_nuw(
-; CHECK-NEXT: [[NOTMASK:%.*]] = shl nuw nsw i32 -1, [[NBITS:%.*]]
-; CHECK-NEXT: [[RET:%.*]] = xor i32 [[NOTMASK]], -1
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 0
;
%setbit = shl nsw i32 1, %NBits
%ret = add nuw i32 %setbit, -1
@@ -96,9 +90,7 @@ define i32 @shl_nsw_add_nuw(i32 %NBits) {
define i32 @shl_nsw_add_nsw_nuw(i32 %NBits) {
; CHECK-LABEL: @shl_nsw_add_nsw_nuw(
-; CHECK-NEXT: [[NOTMASK:%.*]] = shl nuw nsw i32 -1, [[NBITS:%.*]]
-; CHECK-NEXT: [[RET:%.*]] = xor i32 [[NOTMASK]], -1
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 0
;
%setbit = shl nsw i32 1, %NBits
%ret = add nuw nsw i32 %setbit, -1
@@ -131,9 +123,7 @@ define i32 @shl_nuw_add_nsw(i32 %NBits) {
define i32 @shl_nuw_add_nuw(i32 %NBits) {
; CHECK-LABEL: @shl_nuw_add_nuw(
-; CHECK-NEXT: [[NOTMASK:%.*]] = shl nuw nsw i32 -1, [[NBITS:%.*]]
-; CHECK-NEXT: [[RET:%.*]] = xor i32 [[NOTMASK]], -1
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 0
;
%setbit = shl nuw i32 1, %NBits
%ret = add nuw i32 %setbit, -1
@@ -142,9 +132,7 @@ define i32 @shl_nuw_add_nuw(i32 %NBits) {
define i32 @shl_nuw_add_nsw_nuw(i32 %NBits) {
; CHECK-LABEL: @shl_nuw_add_nsw_nuw(
-; CHECK-NEXT: [[NOTMASK:%.*]] = shl nuw nsw i32 -1, [[NBITS:%.*]]
-; CHECK-NEXT: [[RET:%.*]] = xor i32 [[NOTMASK]], -1
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 0
;
%setbit = shl nuw i32 1, %NBits
%ret = add nuw nsw i32 %setbit, -1
@@ -177,9 +165,7 @@ define i32 @shl_nsw_nuw_add_nsw(i32 %NBits) {
define i32 @shl_nsw_nuw_add_nuw(i32 %NBits) {
; CHECK-LABEL: @shl_nsw_nuw_add_nuw(
-; CHECK-NEXT: [[NOTMASK:%.*]] = shl nuw nsw i32 -1, [[NBITS:%.*]]
-; CHECK-NEXT: [[RET:%.*]] = xor i32 [[NOTMASK]], -1
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 0
;
%setbit = shl nuw nsw i32 1, %NBits
%ret = add nuw i32 %setbit, -1
@@ -188,9 +174,7 @@ define i32 @shl_nsw_nuw_add_nuw(i32 %NBits) {
define i32 @shl_nsw_nuw_add_nsw_nuw(i32 %NBits) {
; CHECK-LABEL: @shl_nsw_nuw_add_nsw_nuw(
-; CHECK-NEXT: [[NOTMASK:%.*]] = shl nuw nsw i32 -1, [[NBITS:%.*]]
-; CHECK-NEXT: [[RET:%.*]] = xor i32 [[NOTMASK]], -1
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 0
;
%setbit = shl nuw nsw i32 1, %NBits
%ret = add nuw nsw i32 %setbit, -1
diff --git a/llvm/test/Transforms/InstSimplify/constantfold-shl-nuw-C-to-C.ll b/llvm/test/Transforms/InstSimplify/constantfold-shl-nuw-C-to-C.ll
index 7b56ade8fc4..468a69916b0 100644
--- a/llvm/test/Transforms/InstSimplify/constantfold-shl-nuw-C-to-C.ll
+++ b/llvm/test/Transforms/InstSimplify/constantfold-shl-nuw-C-to-C.ll
@@ -9,8 +9,7 @@
define i8 @shl_nuw (i8 %x) {
; CHECK-LABEL: @shl_nuw(
-; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 -1, [[X:%.*]]
-; CHECK-NEXT: ret i8 [[RET]]
+; CHECK-NEXT: ret i8 -1
;
%ret = shl nuw i8 -1, %x
; nuw here means that %x can only be 0
@@ -19,8 +18,7 @@ define i8 @shl_nuw (i8 %x) {
define i8 @shl_nuw_nsw (i8 %x) {
; CHECK-LABEL: @shl_nuw_nsw(
-; CHECK-NEXT: [[RET:%.*]] = shl nuw nsw i8 -1, [[X:%.*]]
-; CHECK-NEXT: ret i8 [[RET]]
+; CHECK-NEXT: ret i8 -1
;
%ret = shl nuw nsw i8 -1, %x
; nuw here means that %x can only be 0
@@ -29,8 +27,7 @@ define i8 @shl_nuw_nsw (i8 %x) {
define i8 @shl_128 (i8 %x) {
; CHECK-LABEL: @shl_128(
-; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 -128, [[X:%.*]]
-; CHECK-NEXT: ret i8 [[RET]]
+; CHECK-NEXT: ret i8 -128
;
%ret = shl nuw i8 128, %x
; 128 == 1<<7 == just the sign bit is set
@@ -75,8 +72,7 @@ define i8 @knownbits_negativeorzero(i8 %x, i8 %y) {
define <2 x i8> @shl_vec(<2 x i8> %x) {
; CHECK-LABEL: @shl_vec(
-; CHECK-NEXT: [[RET:%.*]] = shl nuw <2 x i8> <i8 -1, i8 -1>, [[X:%.*]]
-; CHECK-NEXT: ret <2 x i8> [[RET]]
+; CHECK-NEXT: ret <2 x i8> <i8 -1, i8 -1>
;
%ret = shl nuw <2 x i8> <i8 -1, i8 -1>, %x
ret <2 x i8> %ret
@@ -84,8 +80,7 @@ define <2 x i8> @shl_vec(<2 x i8> %x) {
define <3 x i8> @shl_vec_undef(<3 x i8> %x) {
; CHECK-LABEL: @shl_vec_undef(
-; CHECK-NEXT: [[RET:%.*]] = shl nuw <3 x i8> <i8 -1, i8 undef, i8 -1>, [[X:%.*]]
-; CHECK-NEXT: ret <3 x i8> [[RET]]
+; CHECK-NEXT: ret <3 x i8> <i8 -1, i8 undef, i8 -1>
;
%ret = shl nuw <3 x i8> <i8 -1, i8 undef, i8 -1>, %x
ret <3 x i8> %ret
@@ -93,8 +88,7 @@ define <3 x i8> @shl_vec_undef(<3 x i8> %x) {
define <2 x i8> @shl_vec_nonsplat(<2 x i8> %x) {
; CHECK-LABEL: @shl_vec_nonsplat(
-; CHECK-NEXT: [[RET:%.*]] = shl nuw <2 x i8> <i8 -1, i8 -2>, [[X:%.*]]
-; CHECK-NEXT: ret <2 x i8> [[RET]]
+; CHECK-NEXT: ret <2 x i8> <i8 -1, i8 -2>
;
%ret = shl nuw <2 x i8> <i8 -1, i8 -2>, %x
ret <2 x i8> %ret
OpenPOWER on IntegriCloud