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It's not safe to coalesce a move where src and dst registers have different subregister indices. e.g.:

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%reg16404:1<def> = MOV8rr %reg16412:2<kill>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91061 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2009-12-10 20:59:45 +00:00
parent e4a70cd19c
commit 6fd78ec8a2
2 changed files with 47 additions and 1 deletions
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8
lib/CodeGen/SimpleRegisterCoalescing.cpp
View File

@ -1317,7 +1317,13 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
"coalesced to another register.\n");
return false; // Not coalescable.
}
} else if (!tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)){
} else if (tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
if (SrcSubIdx && DstSubIdx && SrcSubIdx != DstSubIdx) {
// e.g. %reg16404:1<def> = MOV8rr %reg16412:2<kill>
Again = true;
return false; // Not coalescable.
}
} else {
llvm_unreachable("Unrecognized copy instruction!");
}

40
test/CodeGen/X86/2009-12-12-CoalescerBug.ll Normal file
View File

@ -0,0 +1,40 @@
; RUN: llc < %s -mtriple=i386-apple-darwin | FileCheck %s
define i32 @do_loop(i32* nocapture %sdp, i32* nocapture %ddp, i8* %mdp, i8* nocapture %cdp, i32 %w) nounwind readonly optsize ssp {
entry:
br label %bb
bb: ; preds = %bb5, %entry
%mask.1.in = load i8* undef, align 1 ; <i8> [#uses=3]
%0 = icmp eq i8 %mask.1.in, 0 ; <i1> [#uses=1]
br i1 %0, label %bb5, label %bb1
bb1: ; preds = %bb
br i1 undef, label %bb2, label %bb3
bb2: ; preds = %bb1
; CHECK: %bb2
; CHECK: movb %ch, %al
%1 = zext i8 %mask.1.in to i32 ; <i32> [#uses=1]
%2 = zext i8 undef to i32 ; <i32> [#uses=1]
%3 = mul i32 %2, %1 ; <i32> [#uses=1]
%4 = add i32 %3, 1 ; <i32> [#uses=1]
%5 = add i32 %4, 0 ; <i32> [#uses=1]
%6 = lshr i32 %5, 8 ; <i32> [#uses=1]
%retval12.i = trunc i32 %6 to i8 ; <i8> [#uses=1]
br label %bb3
bb3: ; preds = %bb2, %bb1
%mask.0.in = phi i8 [ %retval12.i, %bb2 ], [ %mask.1.in, %bb1 ] ; <i8> [#uses=1]
%7 = icmp eq i8 %mask.0.in, 0 ; <i1> [#uses=1]
br i1 %7, label %bb5, label %bb4
bb4: ; preds = %bb3
br label %bb5
bb5: ; preds = %bb4, %bb3, %bb
br i1 undef, label %bb6, label %bb
bb6: ; preds = %bb5
ret i32 undef
}