Author: Yingwei Zheng Date: 2024-11-25T09:45:43+01:00 New Revision: 11be11b8773bf63abe2c8da72db3ee7c25af524b
URL: https://github.com/llvm/llvm-project/commit/11be11b8773bf63abe2c8da72db3ee7c25af524b DIFF: https://github.com/llvm/llvm-project/commit/11be11b8773bf63abe2c8da72db3ee7c25af524b.diff LOG: [SCEV] Fix sext handling for `getConstantMultiple` (#117093) Counterexample: 219 is a multiple of 73. But `sext i8 219 to i16 = 65499` is not. Fixes https://github.com/llvm/llvm-project/issues/116483. (cherry picked from commit 458dfbd855806461b4508bf8845cafe0411dbfd4) Added: llvm/test/Analysis/ScalarEvolution/pr116483.ll llvm/test/Transforms/IndVarSimplify/pr116483.ll Modified: llvm/lib/Analysis/ScalarEvolution.cpp Removed: ################################################################################ diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 51cffac8087689..412cfe73d3e559 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -6313,8 +6313,10 @@ APInt ScalarEvolution::getConstantMultipleImpl(const SCEV *S) { return getConstantMultiple(Z->getOperand()).zext(BitWidth); } case scSignExtend: { + // Only multiples that are a power of 2 will hold after sext. const SCEVSignExtendExpr *E = cast<SCEVSignExtendExpr>(S); - return getConstantMultiple(E->getOperand()).sext(BitWidth); + uint32_t TZ = getMinTrailingZeros(E->getOperand()); + return GetShiftedByZeros(TZ); } case scMulExpr: { const SCEVMulExpr *M = cast<SCEVMulExpr>(S); diff --git a/llvm/test/Analysis/ScalarEvolution/pr116483.ll b/llvm/test/Analysis/ScalarEvolution/pr116483.ll new file mode 100644 index 00000000000000..cc2334e9c64f92 --- /dev/null +++ b/llvm/test/Analysis/ScalarEvolution/pr116483.ll @@ -0,0 +1,26 @@ +; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 5 +; RUN: opt -S -disable-output "-passes=print<scalar-evolution>" < %s 2>&1 | FileCheck %s + +define i16 @test() { +; CHECK-LABEL: 'test' +; CHECK-NEXT: Classifying expressions for: @test +; CHECK-NEXT: %xor = xor i32 0, 3 +; CHECK-NEXT: --> %xor U: [3,4) S: [3,4) +; CHECK-NEXT: %mul = mul i32 %xor, 329 +; CHECK-NEXT: --> (329 * %xor)<nuw><nsw> U: [987,988) S: [987,988) +; CHECK-NEXT: %conv = trunc i32 %mul to i16 +; CHECK-NEXT: --> (329 * (trunc i32 %xor to i16))<nuw><nsw> U: [987,988) S: [987,988) +; CHECK-NEXT: %sext = shl i16 %conv, 8 +; CHECK-NEXT: --> (18688 * (trunc i32 %xor to i16))<nuw> U: [-9472,-9471) S: [-9472,-9471) +; CHECK-NEXT: %conv1 = ashr i16 %sext, 8 +; CHECK-NEXT: --> (sext i8 (73 * (trunc i32 %xor to i8))<nuw> to i16) U: [-37,-36) S: [-37,-36) +; CHECK-NEXT: Determining loop execution counts for: @test +; +entry: + %xor = xor i32 0, 3 + %mul = mul i32 %xor, 329 + %conv = trunc i32 %mul to i16 + %sext = shl i16 %conv, 8 + %conv1 = ashr i16 %sext, 8 + ret i16 %conv1 +} diff --git a/llvm/test/Transforms/IndVarSimplify/pr116483.ll b/llvm/test/Transforms/IndVarSimplify/pr116483.ll new file mode 100644 index 00000000000000..ae108a525223e0 --- /dev/null +++ b/llvm/test/Transforms/IndVarSimplify/pr116483.ll @@ -0,0 +1,36 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5 +; RUN: opt -S -passes=indvars < %s | FileCheck %s + +define i32 @test() { +; CHECK-LABEL: define i32 @test() { +; CHECK-NEXT: [[ENTRY:.*:]] +; CHECK-NEXT: [[XOR:%.*]] = xor i32 0, 3 +; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[XOR]], 329 +; CHECK-NEXT: [[CONV:%.*]] = trunc i32 [[MUL]] to i16 +; CHECK-NEXT: [[SEXT:%.*]] = shl i16 [[CONV]], 8 +; CHECK-NEXT: [[CONV1:%.*]] = ashr i16 [[SEXT]], 8 +; CHECK-NEXT: br label %[[LOOP_BODY:.*]] +; CHECK: [[LOOP_BODY]]: +; CHECK-NEXT: br i1 true, label %[[EXIT:.*]], label %[[LOOP_BODY]] +; CHECK: [[EXIT]]: +; CHECK-NEXT: [[CONV3:%.*]] = zext i16 [[CONV1]] to i32 +; CHECK-NEXT: ret i32 [[CONV3]] +; +entry: + %xor = xor i32 0, 3 + %mul = mul i32 %xor, 329 + %conv = trunc i32 %mul to i16 + %sext = shl i16 %conv, 8 + %conv1 = ashr i16 %sext, 8 + %conv3 = zext i16 %conv1 to i32 + br label %loop.body + +loop.body: + %indvar = phi i32 [ %indvar.inc, %loop.body ], [ 1, %entry ] + %indvar.inc = add nuw i32 %indvar, 1 + %exitcond = icmp eq i32 %indvar, %conv3 + br i1 %exitcond, label %exit, label %loop.body + +exit: + ret i32 %conv3 +} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
