[AArch64][LoopIdiom] Disable LoopIdiomTransform when NoImplicitFloat is present #87677
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@llvm/pr-subscribers-backend-aarch64 @llvm/pr-subscribers-llvm-transforms Author: Min-Yih Hsu (mshockwave) ChangesThis behavior is aligned with both LoopVectorizer and SLPVectorizer. Full diff: https://github.com/llvm/llvm-project/pull/87677.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AArch64/AArch64LoopIdiomTransform.cpp b/llvm/lib/Target/AArch64/AArch64LoopIdiomTransform.cpp
index 6dfb2b9df7135d..a9bd8d877fb2ee 100644
--- a/llvm/lib/Target/AArch64/AArch64LoopIdiomTransform.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoopIdiomTransform.cpp
@@ -190,17 +190,23 @@ AArch64LoopIdiomTransformPass::run(Loop &L, LoopAnalysisManager &AM,
bool AArch64LoopIdiomTransform::run(Loop *L) {
CurLoop = L;
- if (DisableAll || L->getHeader()->getParent()->hasOptSize())
+ Function &F = *L->getHeader()->getParent();
+ if (DisableAll || F.hasOptSize())
return false;
+ if (F.hasFnAttribute(Attribute::NoImplicitFloat)) {
+ LLVM_DEBUG(dbgs() << DEBUG_TYPE << " is disabled on " << F.getName()
+ << " due to its NoImplicitFloat attribute");
+ return false;
+ }
+
// If the loop could not be converted to canonical form, it must have an
// indirectbr in it, just give up.
if (!L->getLoopPreheader())
return false;
- LLVM_DEBUG(dbgs() << DEBUG_TYPE " Scanning: F["
- << CurLoop->getHeader()->getParent()->getName()
- << "] Loop %" << CurLoop->getHeader()->getName() << "\n");
+ LLVM_DEBUG(dbgs() << DEBUG_TYPE " Scanning: F[" << F.getName() << "] Loop %"
+ << CurLoop->getHeader()->getName() << "\n");
return recognizeByteCompare();
}
diff --git a/llvm/test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll b/llvm/test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll
index daa64f2e2ea7c0..27ab11446b5719 100644
--- a/llvm/test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll
+++ b/llvm/test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll
@@ -2090,3 +2090,99 @@ while.end:
ret i32 %res
}
+; The optimization should be disabled when noimplicitfloat is present.
+define i32 @no_implicit_float(ptr %a, ptr %b, i32 %len, i32 %extra, i32 %n) noimplicitfloat {
+; CHECK-LABEL: define i32 @no_implicit_float(
+; CHECK-SAME: ptr [[A:%.*]], ptr [[B:%.*]], i32 [[LEN:%.*]], i32 [[EXTRA:%.*]], i32 [[N:%.*]]) #[[ATTR2:[0-9]+]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[WHILE_COND:%.*]]
+; CHECK: while.cond:
+; CHECK-NEXT: [[LEN_ADDR:%.*]] = phi i32 [ [[LEN]], [[ENTRY:%.*]] ], [ [[INC:%.*]], [[WHILE_BODY:%.*]] ]
+; CHECK-NEXT: [[INC]] = add i32 [[LEN_ADDR]], 1
+; CHECK-NEXT: [[CMP_NOT:%.*]] = icmp eq i32 [[INC]], [[N]]
+; CHECK-NEXT: br i1 [[CMP_NOT]], label [[WHILE_END:%.*]], label [[WHILE_BODY]]
+; CHECK: while.body:
+; CHECK-NEXT: [[IDXPROM:%.*]] = zext i32 [[INC]] to i64
+; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i8, ptr [[A]], i64 [[IDXPROM]]
+; CHECK-NEXT: [[TMP0:%.*]] = load i8, ptr [[ARRAYIDX]], align 1
+; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds i8, ptr [[B]], i64 [[IDXPROM]]
+; CHECK-NEXT: [[TMP1:%.*]] = load i8, ptr [[ARRAYIDX2]], align 1
+; CHECK-NEXT: [[CMP_NOT2:%.*]] = icmp eq i8 [[TMP0]], [[TMP1]]
+; CHECK-NEXT: br i1 [[CMP_NOT2]], label [[WHILE_COND]], label [[WHILE_END]]
+; CHECK: while.end:
+; CHECK-NEXT: [[INC_LCSSA:%.*]] = phi i32 [ [[INC]], [[WHILE_BODY]] ], [ [[INC]], [[WHILE_COND]] ]
+; CHECK-NEXT: [[EXTRA_PHI:%.*]] = phi i32 [ [[EXTRA]], [[WHILE_BODY]] ], [ [[EXTRA]], [[WHILE_COND]] ]
+; CHECK-NEXT: [[RES:%.*]] = add i32 [[INC_LCSSA]], [[EXTRA_PHI]]
+; CHECK-NEXT: ret i32 [[RES]]
+;
+; LOOP-DEL-LABEL: define i32 @no_implicit_float(
+; LOOP-DEL-SAME: ptr [[A:%.*]], ptr [[B:%.*]], i32 [[LEN:%.*]], i32 [[EXTRA:%.*]], i32 [[N:%.*]]) #[[ATTR2:[0-9]+]] {
+; LOOP-DEL-NEXT: entry:
+; LOOP-DEL-NEXT: br label [[WHILE_COND:%.*]]
+; LOOP-DEL: while.cond:
+; LOOP-DEL-NEXT: [[LEN_ADDR:%.*]] = phi i32 [ [[LEN]], [[ENTRY:%.*]] ], [ [[INC:%.*]], [[WHILE_BODY:%.*]] ]
+; LOOP-DEL-NEXT: [[INC]] = add i32 [[LEN_ADDR]], 1
+; LOOP-DEL-NEXT: [[CMP_NOT:%.*]] = icmp eq i32 [[INC]], [[N]]
+; LOOP-DEL-NEXT: br i1 [[CMP_NOT]], label [[WHILE_END:%.*]], label [[WHILE_BODY]]
+; LOOP-DEL: while.body:
+; LOOP-DEL-NEXT: [[IDXPROM:%.*]] = zext i32 [[INC]] to i64
+; LOOP-DEL-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i8, ptr [[A]], i64 [[IDXPROM]]
+; LOOP-DEL-NEXT: [[TMP0:%.*]] = load i8, ptr [[ARRAYIDX]], align 1
+; LOOP-DEL-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds i8, ptr [[B]], i64 [[IDXPROM]]
+; LOOP-DEL-NEXT: [[TMP1:%.*]] = load i8, ptr [[ARRAYIDX2]], align 1
+; LOOP-DEL-NEXT: [[CMP_NOT2:%.*]] = icmp eq i8 [[TMP0]], [[TMP1]]
+; LOOP-DEL-NEXT: br i1 [[CMP_NOT2]], label [[WHILE_COND]], label [[WHILE_END]]
+; LOOP-DEL: while.end:
+; LOOP-DEL-NEXT: [[INC_LCSSA:%.*]] = phi i32 [ [[INC]], [[WHILE_BODY]] ], [ [[INC]], [[WHILE_COND]] ]
+; LOOP-DEL-NEXT: [[EXTRA_PHI:%.*]] = phi i32 [ [[EXTRA]], [[WHILE_BODY]] ], [ [[EXTRA]], [[WHILE_COND]] ]
+; LOOP-DEL-NEXT: [[RES:%.*]] = add i32 [[INC_LCSSA]], [[EXTRA_PHI]]
+; LOOP-DEL-NEXT: ret i32 [[RES]]
+;
+; NO-TRANSFORM-LABEL: define i32 @no_implicit_float(
+; NO-TRANSFORM-SAME: ptr [[A:%.*]], ptr [[B:%.*]], i32 [[LEN:%.*]], i32 [[EXTRA:%.*]], i32 [[N:%.*]]) #[[ATTR1:[0-9]+]] {
+; NO-TRANSFORM-NEXT: entry:
+; NO-TRANSFORM-NEXT: br label [[WHILE_COND:%.*]]
+; NO-TRANSFORM: while.cond:
+; NO-TRANSFORM-NEXT: [[LEN_ADDR:%.*]] = phi i32 [ [[LEN]], [[ENTRY:%.*]] ], [ [[INC:%.*]], [[WHILE_BODY:%.*]] ]
+; NO-TRANSFORM-NEXT: [[INC]] = add i32 [[LEN_ADDR]], 1
+; NO-TRANSFORM-NEXT: [[CMP_NOT:%.*]] = icmp eq i32 [[INC]], [[N]]
+; NO-TRANSFORM-NEXT: br i1 [[CMP_NOT]], label [[WHILE_END:%.*]], label [[WHILE_BODY]]
+; NO-TRANSFORM: while.body:
+; NO-TRANSFORM-NEXT: [[IDXPROM:%.*]] = zext i32 [[INC]] to i64
+; NO-TRANSFORM-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i8, ptr [[A]], i64 [[IDXPROM]]
+; NO-TRANSFORM-NEXT: [[TMP0:%.*]] = load i8, ptr [[ARRAYIDX]], align 1
+; NO-TRANSFORM-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds i8, ptr [[B]], i64 [[IDXPROM]]
+; NO-TRANSFORM-NEXT: [[TMP1:%.*]] = load i8, ptr [[ARRAYIDX2]], align 1
+; NO-TRANSFORM-NEXT: [[CMP_NOT2:%.*]] = icmp eq i8 [[TMP0]], [[TMP1]]
+; NO-TRANSFORM-NEXT: br i1 [[CMP_NOT2]], label [[WHILE_COND]], label [[WHILE_END]]
+; NO-TRANSFORM: while.end:
+; NO-TRANSFORM-NEXT: [[INC_LCSSA:%.*]] = phi i32 [ [[INC]], [[WHILE_BODY]] ], [ [[INC]], [[WHILE_COND]] ]
+; NO-TRANSFORM-NEXT: [[EXTRA_PHI:%.*]] = phi i32 [ [[EXTRA]], [[WHILE_BODY]] ], [ [[EXTRA]], [[WHILE_COND]] ]
+; NO-TRANSFORM-NEXT: [[RES:%.*]] = add i32 [[INC_LCSSA]], [[EXTRA_PHI]]
+; NO-TRANSFORM-NEXT: ret i32 [[RES]]
+;
+entry:
+ br label %while.cond
+
+while.cond:
+ %len.addr = phi i32 [ %len, %entry ], [ %inc, %while.body ]
+ %inc = add i32 %len.addr, 1
+ %cmp.not = icmp eq i32 %inc, %n
+ br i1 %cmp.not, label %while.end, label %while.body
+
+while.body:
+ %idxprom = zext i32 %inc to i64
+ %arrayidx = getelementptr inbounds i8, ptr %a, i64 %idxprom
+ %0 = load i8, ptr %arrayidx
+ %arrayidx2 = getelementptr inbounds i8, ptr %b, i64 %idxprom
+ %1 = load i8, ptr %arrayidx2
+ %cmp.not2 = icmp eq i8 %0, %1
+ br i1 %cmp.not2, label %while.cond, label %while.end
+
+while.end:
+ %inc.lcssa = phi i32 [ %inc, %while.body ], [ %inc, %while.cond ]
+ %extra.phi = phi i32 [ %extra, %while.body ], [ %extra, %while.cond ]
+ %res = add i32 %inc.lcssa, %extra.phi
+ ret i32 %res
+}
+
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LGTM, but I'd like @david-arm to agree. implicitfloat attribute documentation from LangRef.
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This behavior is aligned with both LoopVectorizer and SLPVectorizer.