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refactor(codegen-native): extract EmitStaticElemScale for static-array indexing

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Phase 1 item 5 of the de-duplication plan.  The read-path static-array
subscript scaling — `if SAT.LowBound <> 0 then subq $lowbound; imulq $elemsize`
applied to an index already in %rax — was spelled out at 7 sites, each casting
a different expression to TStaticArrayTypeDesc.  Collapse the body into
EmitStaticElemScale(ASAT) and pass the resolved type.

Only the read sites are touched: the static-array STORE paths compute the
element size from a precomputed DAElemType local rather than
ASAT.ElementType.RawSize(), so they are deliberately left as-is (the imulq
operand differs).

Proven byte-identical: native .s for a static-array program (non-zero low
bounds, integer + double + record-nested arrays, read and write) is identical
to pre-refactor HEAD.  All four self-host fixpoints pass; full suite OK (3853
tests) on both QBE-built and native-built test runners.
This commit is contained in:
Graeme Geldenhuys 2026-06-27 09:09:07 +01:00
parent 8a32c3ab57
commit fdcce09254
1 changed files with 19 additions and 34 deletions
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53
compiler/src/main/pascal/blaise.codegen.native.x86_64.pas
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@ -389,6 +389,10 @@ type
compound-body inline idiom used for try/finally/except bodies, loop
bodies, the program block, and unit init sections. Nil AList is a no-op. }
procedure EmitStmtList(AList: TObjectList);
{ Given a static-array element index already in %rax, scale it to a byte
offset: subtract the (non-zero) low bound, then multiply by the element
size. The read-path subscript sites all spell this the same way. }
procedure EmitStaticElemScale(ASAT: TStaticArrayTypeDesc);
{ Lower a Write/WriteLn call (ANewline = WriteLn). }
procedure EmitWrite(ACall: TProcCall; ANewline: Boolean);
{ Lower a for loop. }
@ -3551,9 +3555,7 @@ var
begin
SAT := TStaticArrayTypeDesc(ASub.StrExpr.ResolvedType);
Self.EmitExprToEax(ASub.IndexExpr); { index -> %rax }
if SAT.LowBound <> 0 then
Self.Emit(Format(#9'subq $%d, %%rax', [SAT.LowBound]));
Self.Emit(Format(#9'imulq $%d, %%rax', [SAT.ElementType.RawSize()]));
Self.EmitStaticElemScale(SAT);
{ Base address of the array's inline storage into %rcx. }
if (ASub.StrExpr is TIdentExpr) and
TIdentExpr(ASub.StrExpr).IsImplicitSelf and
@ -5088,14 +5090,8 @@ begin
Self.EmitExprToEax(TStringSubscriptExpr(AExpr).StrExpr);
Self.Emit(#9'pushq %rax');
Self.EmitExprToEax(TStringSubscriptExpr(AExpr).IndexExpr);
if TStaticArrayTypeDesc(
TStringSubscriptExpr(AExpr).StrExpr.ResolvedType).LowBound <> 0 then
Self.Emit(Format(#9'subq $%d, %%rax',
[TStaticArrayTypeDesc(
TStringSubscriptExpr(AExpr).StrExpr.ResolvedType).LowBound]));
Self.Emit(Format(#9'imulq $%d, %%rax',
[TStaticArrayTypeDesc(TStringSubscriptExpr(AExpr).StrExpr.ResolvedType)
.ElementType.RawSize()]));
Self.EmitStaticElemScale(
TStaticArrayTypeDesc(TStringSubscriptExpr(AExpr).StrExpr.ResolvedType));
Self.Emit(#9'popq %rcx');
Self.Emit(#9'addq %rcx, %rax');
Self.EmitLoadFloat('(%rax)',
@ -6957,11 +6953,7 @@ begin
Self.EmitExprToEax(SAE.StrExpr);
Self.Emit(#9'pushq %rax');
Self.EmitExprToEax(SAE.IndexExpr);
if TStaticArrayTypeDesc(SAE.StrExpr.ResolvedType).LowBound <> 0 then
Self.Emit(Format(#9'subq $%d, %%rax',
[TStaticArrayTypeDesc(SAE.StrExpr.ResolvedType).LowBound]));
Self.Emit(Format(#9'imulq $%d, %%rax',
[TStaticArrayTypeDesc(SAE.StrExpr.ResolvedType).ElementType.RawSize()]));
Self.EmitStaticElemScale(TStaticArrayTypeDesc(SAE.StrExpr.ResolvedType));
Self.Emit(#9'popq %rcx');
Self.Emit(#9'addq %rcx, %rax');
{ Record and nested static-array elements evaluate to their address —
@ -7026,9 +7018,7 @@ begin
begin
SCAT := TStaticArrayTypeDesc(FAE.ConstArrayType);
Self.EmitExprToEax(FAE.PropIndexExpr); { index -> %rax }
if SCAT.LowBound <> 0 then
Self.Emit(Format(#9'subq $%d, %%rax', [SCAT.LowBound]));
Self.Emit(Format(#9'imulq $%d, %%rax', [SCAT.ElementType.RawSize()]));
Self.EmitStaticElemScale(SCAT);
Self.Emit(Format(#9'leaq %s(%%rip), %%rcx',
[NativeMangle(FAE.ConstArraySymbol)]));
Self.Emit(#9'addq %rcx, %rax');
@ -7292,11 +7282,7 @@ begin
begin
Self.Emit(#9'pushq %rcx');
Self.EmitExprToEax(FAE.PropIndexExpr);
if TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc).LowBound <> 0 then
Self.Emit(Format(#9'subq $%d, %%rax',
[TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc).LowBound]));
Self.Emit(Format(#9'imulq $%d, %%rax',
[TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc).ElementType.RawSize()]));
Self.EmitStaticElemScale(TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc));
Self.Emit(#9'popq %rcx');
Self.Emit(#9'addq %rcx, %rax');
if TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc).ElementType.Kind = tyRecord then
@ -7573,11 +7559,7 @@ begin
Self.EmitExprToEax(SAE.StrExpr);
Self.Emit(#9'pushq %rax');
Self.EmitExprToEax(SAE.IndexExpr);
if TStaticArrayTypeDesc(SAE.StrExpr.ResolvedType).LowBound <> 0 then
Self.Emit(Format(#9'subq $%d, %%rax',
[TStaticArrayTypeDesc(SAE.StrExpr.ResolvedType).LowBound]));
Self.Emit(Format(#9'imulq $%d, %%rax',
[TStaticArrayTypeDesc(SAE.StrExpr.ResolvedType).ElementType.RawSize()]));
Self.EmitStaticElemScale(TStaticArrayTypeDesc(SAE.StrExpr.ResolvedType));
Self.Emit(#9'popq %rcx');
Self.Emit(#9'addq %rcx, %rax');
Exit;
@ -7713,11 +7695,7 @@ begin
begin
Self.Emit(#9'pushq %rcx');
Self.EmitExprToEax(FAE.PropIndexExpr);
if TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc).LowBound <> 0 then
Self.Emit(Format(#9'subq $%d, %%rax',
[TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc).LowBound]));
Self.Emit(Format(#9'imulq $%d, %%rax',
[TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc).ElementType.RawSize()]));
Self.EmitStaticElemScale(TStaticArrayTypeDesc(FAE.FieldInfo.TypeDesc));
Self.Emit(#9'popq %rcx');
Self.Emit(#9'addq %rcx, %rax');
end
@ -10811,6 +10789,13 @@ begin
Self.EmitStmt(TASTStmt(AList.Items[I]));
end;
procedure TX86_64Backend.EmitStaticElemScale(ASAT: TStaticArrayTypeDesc);
begin
if ASAT.LowBound <> 0 then
Self.Emit(Format(#9'subq $%d, %%rax', [ASAT.LowBound]));
Self.Emit(Format(#9'imulq $%d, %%rax', [ASAT.ElementType.RawSize()]));
end;
procedure TX86_64Backend.EmitStmt(AStmt: TASTStmt);
var
PC: TProcCall;