[llvm] 22e4346 - [ValueTracking] Add tracking of the alignment assume bundle
Alex Richardson via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 27 05:17:42 PDT 2020
Author: Shimin Cui
Date: 2020-10-27T12:16:45Z
New Revision: 22e4346e054a4474a68fd293324db295fffed34c
URL: https://github.com/llvm/llvm-project/commit/22e4346e054a4474a68fd293324db295fffed34c
DIFF: https://github.com/llvm/llvm-project/commit/22e4346e054a4474a68fd293324db295fffed34c.diff
LOG: [ValueTracking] Add tracking of the alignment assume bundle
This patch is to add the support of the value tracking of the alignment assume bundle.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D88669
Added:
llvm/test/Transforms/InstCombine/assume-align.ll
Modified:
llvm/lib/Analysis/ValueTracking.cpp
llvm/test/Analysis/BasicAA/featuretest.ll
llvm/test/Analysis/ValueTracking/assume-queries-counter.ll
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 23642084cecd..dc252a281c4d 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -670,6 +670,14 @@ static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known,
unsigned BitWidth = Known.getBitWidth();
+ // Refine Known set if the pointer alignment is set by assume bundles.
+ if (V->getType()->isPointerTy()) {
+ if (RetainedKnowledge RK = getKnowledgeValidInContext(
+ V, {Attribute::Alignment}, Q.CxtI, Q.DT, Q.AC)) {
+ Known.Zero.setLowBits(Log2_32(RK.ArgValue));
+ }
+ }
+
// Note that the patterns below need to be kept in sync with the code
// in AssumptionCache::updateAffectedValues.
diff --git a/llvm/test/Analysis/BasicAA/featuretest.ll b/llvm/test/Analysis/BasicAA/featuretest.ll
index 9c438e1ec689..006274fc5fab 100644
--- a/llvm/test/Analysis/BasicAA/featuretest.ll
+++ b/llvm/test/Analysis/BasicAA/featuretest.ll
@@ -128,7 +128,7 @@ define i32 @gep_distance_test3(i32 * %A) {
; USE_ASSUME-LABEL: @gep_distance_test3(
; USE_ASSUME-NEXT: [[C1:%.*]] = getelementptr i32, i32* [[A:%.*]], i64 1
; USE_ASSUME-NEXT: [[C:%.*]] = bitcast i32* [[C1]] to i8*
-; USE_ASSUME-NEXT: store i8 42, i8* [[C]], align 1
+; USE_ASSUME-NEXT: store i8 42, i8* [[C]], align 4
; USE_ASSUME-NEXT: call void @llvm.assume(i1 true) [ "dereferenceable"(i32* [[A]], i64 4), "nonnull"(i32* [[A]]), "align"(i32* [[A]], i64 4) ]
; USE_ASSUME-NEXT: ret i32 0
;
diff --git a/llvm/test/Analysis/ValueTracking/assume-queries-counter.ll b/llvm/test/Analysis/ValueTracking/assume-queries-counter.ll
index d234205648c7..a1f97dd3174f 100644
--- a/llvm/test/Analysis/ValueTracking/assume-queries-counter.ll
+++ b/llvm/test/Analysis/ValueTracking/assume-queries-counter.ll
@@ -2,8 +2,8 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instcombine --debug-counter=assume-queries-counter-skip=0,assume-queries-counter-count=1 -S | FileCheck %s --check-prefixes=SAME,COUNTER1
-; RUN: opt < %s -instcombine --debug-counter=assume-queries-counter-skip=1,assume-queries-counter-count=2 -S | FileCheck %s --check-prefixes=SAME,COUNTER2
-; RUN: opt < %s -instcombine --debug-counter=assume-queries-counter-skip=2,assume-queries-counter-count=1 -S | FileCheck %s --check-prefixes=SAME,COUNTER3
+; RUN: opt < %s -instcombine --debug-counter=assume-queries-counter-skip=1,assume-queries-counter-count=6 -S | FileCheck %s --check-prefixes=SAME,COUNTER2
+; RUN: opt < %s -instcombine --debug-counter=assume-queries-counter-skip=6,assume-queries-counter-count=1 -S | FileCheck %s --check-prefixes=SAME,COUNTER3
declare i1 @get_val()
declare void @llvm.assume(i1)
diff --git a/llvm/test/Transforms/InstCombine/assume-align.ll b/llvm/test/Transforms/InstCombine/assume-align.ll
new file mode 100644
index 000000000000..172bd71a6650
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/assume-align.ll
@@ -0,0 +1,80 @@
+; RUN: opt -S -passes=instcombine,simplify-cfg < %s 2>&1 | FileCheck %s
+
+declare void @llvm.assume(i1 noundef)
+
+define void @f1(i8* %a) {
+; CHECK-LABEL: @f1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[PTR:%.*]] = getelementptr inbounds i8, i8* [[A:%.*]], i64 4
+; CHECK-NEXT: [[TMP0:%.*]] = ptrtoint i8* [[PTR]] to i64
+; CHECK-NEXT: [[TMP1:%.*]] = and i64 [[TMP0]], 3
+; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i64 [[TMP1]], 0
+; CHECK-NEXT: br i1 [[TMP2]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
+; CHECK: if.then:
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(i8* [[PTR]], i64 4) ]
+; CHECK-NEXT: [[TMP3:%.*]] = bitcast i8* [[PTR]] to i32*
+; CHECK-NEXT: store i32 4, i32* [[TMP3]], align 4
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: ret void
+;
+entry:
+ %ptr = getelementptr inbounds i8, i8* %a, i64 4
+ %0 = ptrtoint i8* %ptr to i64
+ %1 = and i64 %0, 3
+ %2 = icmp eq i64 %1, 0
+ br i1 %2, label %if.then, label %if.end
+
+if.then: ; preds = %entry
+ call void @llvm.assume(i1 true) [ "align"(i8* %ptr, i64 4) ]
+ %3 = ptrtoint i8* %ptr to i64
+ %4 = and i64 %3, 3
+ %5 = icmp eq i64 %4, 0
+ br i1 %5, label %if.then1, label %if.else1
+
+if.then1: ; preds = %if.then
+ %6 = bitcast i8* %ptr to i32*
+ store i32 4, i32* %6, align 4
+ br label %if.end
+
+if.else1: ; preds = %if.then
+ store i8 1, i8* %ptr, align 1
+ br label %if.end
+
+if.end: ; preds = %if.then1, %if.else1, %entry
+ ret void
+}
+
+; TODO: We could fold away the branch "br i1 %3, ..." by either using a GEP or make getKnowledgeValidInContext aware the alignment bundle offset, and the improvement of value tracking of GEP.
+
+define void @f2(i8* %a) {
+; CHECK-LABEL: @f2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(i8* [[A:%.*]], i64 32, i32 24) ]
+; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds i8, i8* [[A]], i64 8
+; CHECK-NEXT: [[TMP1:%.*]] = ptrtoint i8* [[TMP0]] to i64
+; CHECK-NEXT: [[TMP2:%.*]] = and i64 [[TMP1]], 8
+; CHECK-NEXT: [[TMP3:%.*]] = icmp eq i64 [[TMP2]], 0
+; CHECK-NEXT: br i1 [[TMP3]], label [[IF_THEN1:%.*]], label [[IF_ELSE1:%.*]]
+;
+entry:
+ call void @llvm.assume(i1 true) [ "align"(i8* %a, i64 32, i32 24) ]
+ %0 = getelementptr inbounds i8, i8* %a, i64 8
+ %1 = ptrtoint i8* %0 to i64
+ %2 = and i64 %1, 15
+ %3 = icmp eq i64 %2, 0
+ br i1 %3, label %if.then, label %if.else
+
+if.then: ; preds = %entry
+ %4 = bitcast i8* %0 to i64*
+ store i64 16, i64* %4, align 4
+ br label %if.end
+
+if.else: ; preds = %entry
+ store i8 1, i8* %0, align 1
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ ret void
+}
+
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