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[PowerPC] Option for enabling absolute jumptables with command line 

This option allows the user to specify the use of absolute jumptables instead
of relative which is the default on most PPC subtargets.

Patch by Kamauu Bridgeman

Differential revision: https://reviews.llvm.org/D69108
This commit is contained in:
Nemanja Ivanovic 2019-11-07 19:31:00 -06:00
parent 7215b7ef53
commit 9af28400d6
2 changed files with 105 additions and 0 deletions
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5
llvm/lib/Target/PowerPC/PPCISelLowering.cpp
View File

@ -119,6 +119,9 @@ cl::desc("don't always align innermost loop to 32 bytes on ppc"), cl::Hidden);
static cl::opt<bool> EnableQuadPrecision("enable-ppc-quad-precision",
cl::desc("enable quad precision float support on ppc"), cl::Hidden);
static cl::opt<bool> UseAbsoluteJumpTables("ppc-use-absolute-jumptables",
cl::desc("use absolute jump tables on ppc"), cl::Hidden);
STATISTIC(NumTailCalls, "Number of tail calls");
STATISTIC(NumSiblingCalls, "Number of sibling calls");
@ -2744,6 +2747,8 @@ unsigned PPCTargetLowering::getJumpTableEncoding() const {
}
bool PPCTargetLowering::isJumpTableRelative() const {
if (UseAbsoluteJumpTables)
return false;
if (Subtarget.isPPC64())
return true;
return TargetLowering::isJumpTableRelative();

100
llvm/test/CodeGen/PowerPC/absol-jump-table-enabled.ll Normal file
View File

@ -0,0 +1,100 @@
; NOTE: This test case generates a jump table on PowerPC big and little endian
; NOTE: then verifies that the command line option to enable absolute jump
; NOTE: table works correctly.
; RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -o - \
; RUN: -ppc-use-absolute-jumptables -ppc-asm-full-reg-names \
; RUN: -verify-machineinstrs %s | FileCheck %s -check-prefix=CHECK-LE
; RUN: llc -mtriple=powerpc64-unknown-linux-gnu -o - \
; RUN: -ppc-use-absolute-jumptables -ppc-asm-full-reg-names \
; RUN: -verify-machineinstrs %s | FileCheck %s -check-prefix=CHECK-BE
%struct.node = type { i8, %struct.node* }
; Function Attrs: norecurse nounwind readonly
define zeroext i32 @jumpTableTest(%struct.node* readonly %list) {
; CHECK-LE-LABEL: jumpTableTest:
; CHECK-LE: # %bb.0: # %entry
; CHECK-LE: rldic r[[REG:[0-9]+]], r[[REG]], 3, 29
; CHECK-LE: ldx r[[REG]], r[[REG]], r[[REG1:[0-9]+]]
; CHECK-LE: mtctr r[[REG]]
; CHECK-LE: bctr
; CHECK-LE: blr
;
; CHECK-BE-LABEL: jumpTableTest:
; CHECK-BE: # %bb.0: # %entry
; CHECK-BE: rldic r[[REG:[0-9]+]], r[[REG]], 2, 30
; CHECK-BE: lwax r[[REG]], r[[REG]], r[[REG1:[0-9]+]]
; CHECK-BE: mtctr r[[REG]]
; CHECK-BE: bctr
; CHECK-BE: blr
entry:
%cmp36 = icmp eq %struct.node* %list, null
br i1 %cmp36, label %while.end, label %while.body
while.body: ; preds = %entry, %sw.epilog
%result.038 = phi i32 [ %result.1, %sw.epilog ], [ 0, %entry ]
%current.037 = phi %struct.node* [ %spec.store.select, %sw.epilog ], [ %list, %entry ]
%next1 = getelementptr inbounds %struct.node, %struct.node* %current.037, i64 0, i32 1
%0 = load %struct.node*, %struct.node** %next1, align 8
%cmp2 = icmp eq %struct.node* %0, %current.037
%spec.store.select = select i1 %cmp2, %struct.node* null, %struct.node* %0
%type = getelementptr inbounds %struct.node, %struct.node* %current.037, i64 0, i32 0
%1 = load i8, i8* %type, align 8
switch i8 %1, label %sw.epilog [
i8 1, label %sw.bb
i8 2, label %sw.bb3
i8 3, label %sw.bb5
i8 4, label %sw.bb7
i8 5, label %sw.bb9
i8 6, label %sw.bb11
i8 7, label %sw.bb13
i8 8, label %sw.bb15
i8 9, label %sw.bb17
]
sw.bb: ; preds = %while.body
%add = add nsw i32 %result.038, 13
br label %sw.epilog
sw.bb3: ; preds = %while.body
%add4 = add nsw i32 %result.038, 5
br label %sw.epilog
sw.bb5: ; preds = %while.body
%add6 = add nsw i32 %result.038, 2
br label %sw.epilog
sw.bb7: ; preds = %while.body
%add8 = add nsw i32 %result.038, 7
br label %sw.epilog
sw.bb9: ; preds = %while.body
%add10 = add nsw i32 %result.038, 11
br label %sw.epilog
sw.bb11: ; preds = %while.body
%add12 = add nsw i32 %result.038, 17
br label %sw.epilog
sw.bb13: ; preds = %while.body
%add14 = add nsw i32 %result.038, 16
br label %sw.epilog
sw.bb15: ; preds = %while.body
%add16 = add nsw i32 %result.038, 81
br label %sw.epilog
sw.bb17: ; preds = %while.body
%add18 = add nsw i32 %result.038, 72
br label %sw.epilog
sw.epilog: ; preds = %while.body, %sw.bb17, %sw.bb15, %sw.bb13, %sw.bb11, %sw.bb9, %sw.bb7, %sw.bb5, %sw.bb3, %sw.bb
%result.1 = phi i32 [ %result.038, %while.body ], [ %add18, %sw.bb17 ], [ %add16, %sw.bb15 ], [ %add14, %sw.bb13 ], [ %add12, %sw.bb11 ], [ %add10, %sw.bb9 ], [ %add8, %sw.bb7 ], [ %add6, %sw.bb5 ], [ %add4, %sw.bb3 ], [ %add, %sw.bb ]
%cmp = icmp eq %struct.node* %spec.store.select, null
br i1 %cmp, label %while.end, label %while.body
while.end: ; preds = %sw.epilog, %entry
%result.0.lcssa = phi i32 [ 0, %entry ], [ %result.1, %sw.epilog ]
ret i32 %result.0.lcssa
}